Tris(pentafluoroethyl)difluorophosphorane for fluoride abstraction and ligand exchange reactions of N-heterocyclic carbene and cyclic alkyl(amino)carbene copper(I) fluorides

Abstract

The synthesis and structural characterization of a variety of N-heterocyclic carbene (NHC)- and cyclic (alkyl)(amino)carbene (cAAC)-ligated cationic copper(I) complexes, featuring the weakly coordinating tris(pentafluoroethyl)trifluorophosphate counteranion (FAP⁻ anion, [(C₂F₅)₃PF₃]⁻) are reported. Starting with the complex [(IDipp)Cu(C₆Me₆)]⁺FAP⁻ (IIa) reported previously, (S. A. Föhrenbacher, M. J. Krahfuss, L. Zapf, A. Friedrich, N. V. Ignat'ev, M. Finze and U. Radius, Chem. – Eur. J., 2021, 27, 3504-3516) a series of mononuclear complexes [(IDipp)Cu(LB)]⁺FAP⁻ (IDipp = 1,3-bis(2,6-di-iso-propylphenyl)-imidazolin-2-ylidene) were obtained via ligand exchange of C₆Me₆ with neutral two valence electron (2 VE) donor molecules (LB = NH₃, 1; C₆H₁₂N₂ = DABCO, 2; C₇H₁₀N₂ = DMAP, 3; C₄H₄N₂ = pyrazine, 4; C₁₃H₉N = acridine, 5; η¹-O=C₁₃H₉N = acridone, 6; C₄H₁₀S = SEt₂, 7; C₄H₈S = THT, 8; PCy₃, 9), alongside the dinuclear species [{(IDipp)Cu}₂(C₂N₃H₃)₂]²⁺2FAP⁻ (10) with 1,2,4-triazole. In a parallel strategy, [(cAAC^Me)Cu(C₆Me₆)]⁺FAP⁻ (IIb) was employed as precursor for Cu(I) complex formation, leading to [(cAAC^Me)Cu(LB)]⁺FAP⁻ (LB = C₇H₁₀N₂, 13; C₄H₁₀S, 14) and the dinuclear complexes [{(cAAC^Me)Cu}₂(C₆H₁₂N₂)]²⁺2FAP⁻ (11) and [{(cAAC^Me)Cu}₂(C₄H₄N₂)]²⁺2FAP⁻ (12). Additionally, the reaction of [(carbene)CuF] with (C₂F₅)₃PF₂ in the presence of different 2 VE donor ligands induced fluoride replacement with a 2 VE donor ligand (LB). This strategy facilitated the isolation of a broad range of complexes of the type [(carbene)Cu(LB)]⁺FAP⁻, including [(IDipp)Cu(LB)]⁺FAP⁻ (LB = (N≡CMe)₂, 16; N≡CPh, 17; NH₂Ph, 18; NHPh₂, 21; NC₅H₅, 22; NC₅H₃F₂, 24; NC₅H₂F₃, 25; η¹-O=CPh₂, 27), [(SIDipp)Cu(NH₂Ph)]⁺FAP⁻ (19) (SIDipp = 1,3-bis(2,6-di-iso-propylphenyl)-imidazolidin-2-ylidene) and [(cAAC^Me)Cu(LB)]⁺FAP⁻ (cAAC^Me = 1-(2,6-di-iso-propylphenyl)-3,3,5,5-tetramethyl-pyrrolidin-2-ylidene; LB = N≡CMe, 15; NH₂Ph, 20; NC₅H₅, 23; THF, 28). Additionally, the dinuclear complex [{(IDipp)Cu(μ-ONC₅H₅)}₂]²⁺2FAP⁻ (26) was obtained upon reaction with pyridine-N-oxide. In all cases the carbene ligand stayed intact and the formation of Lewis acid/base pairs of the 2 VE ligand and (C₂F₅)₃PF₂ was never observed. As a result, mixtures of [(carbene)CuF] and (C₂F₅)₃PF₂ may serve as synthons for [(carbene)Cu]⁺, as demonstrated in this work.

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Introduction

Lewis acids (LAs) were originally defined by Gilbert N. Lewis as electron pair acceptors that exhibit a strong propensity to form bonds with electronegative electron pair donors, known as Lewis bases (LBs).² The combination of a LA and a LB with both low to moderate steric demand typically results in the formation of classical Lewis acid/base adducts, characterized by stable covalent bonding interactions. However, when sterically more hindered LA/LB entities are combined, such as PPh₃ with B(C₆F₅)₃, intramolecular interactions are reduced, leading to the formation of weakly bound adducts. These systems often exhibit elongated bond distances, equilibria between the free acid and base, or structural rearrangement, as exemplified by the zwitterionic species Ph₃PH–C₆F₄–BF(C₆F₅)₂.³ Such systems are classified as Frustrated Lewis Pairs (FLPs), where steric constraints prevent complete Lewis acid/base adduct formation, resulting in highly reactive centers with unique chemical properties. This phenomenon enables the activation of otherwise inert small molecules, including H₂,⁴ CO,⁵ CO₂,^6,7 N₂O,^7,8 or SO₂.⁹ To further rationalize the formation of Lewis acid/base adducts while accounting for steric effects, we recently developed a novel and, to date, the first generalizable and experimentally accessible approach.¹⁰ The Lewis Acid/Base Repulsion (LAB-Rep) model utilizes the percent buried volume (%V_bur) as a quantitative measure of steric hindrance and relies on readily available structural data, such as crystallographic information or computationally derived structures. This model enables the estimation of steric constraints that may impede Lewis acid/base interactions, providing valuable insights, particularly in the context of FLP chemistry.

The chemistry of Lewis acid/base combinations involving N-heterocyclic carbenes (NHCs) has been extensively studied, particularly in the context of classical adduct-type complexes with p-block elements. To date, numerous well-characterized examples exist, most of them with group 13 and 15 Lewis acids, such as BF₃, AlCl₃, PF₅, AsF₅, and SbF₅. However, Lewis acid/base adducts of phosphoranes (PR₅) with NHCs remain comparatively rare, and only a limited number exhibit FLP behavior.¹¹ In 2021, we expanded the scope of such systems by isolating a series of NHC-phosphorane adducts (C₂F₅)₃PF₂·NHC via the straightforward reaction of free (small) NHCs with the readily available and highly Lewis-acidic tris(pentafluoroethyl)difluorophosphorane, (C₂F₅)₃PF₂, in Et₂O. Furthermore, mixtures of (C₂F₅)₃PF₂ with sterically demanding NHCs, such as ItBu (ItBu = 1,3-di-tert-butylimidazolin-2-ylidene), IDipp, and SIDipp, exhibited FLP reactivity, facilitating the deprotonation of acetonitrile and other C–H acidic compounds (e.g., acetone, ethyl acetate) to form the corresponding imidazolium salts and [(C₂F₅)₃PF₂(R)]⁻ (R = CH₂CN, OC(=CH₂)CH₃, CH₂CO₂Et).¹²

Recently, we reported on the reaction of (C₂F₅)₃PF₂ with the copper fluoride complexes [(IDipp)CuF] (Ia), [(SIDipp)CuF] (Ib) and [(cAAC^Me)CuF] (Ic) in the presence of various carbon-based ligands LB, such as alkynes and benzenes.¹³ This reaction facilitated fluoride transfer, yielding the corresponding tris(pentafluoroethyl)trifluorophosphate (FAP⁻, [(C₂F₅)₃PF₃]⁻) salts of the copper complex cations [(carbene)Cu(LB)]⁺. Due to the relatively weak interaction between the neutral carbon co-ligand and the metal center, these complexes serve as isolable synthons for cationic [(carbene)Cu]⁺. Furthermore, the hexamethylbenzene complexes [(IDipp)Cu(C₆Me₆)]⁺FAP⁻ (IIa) and [(cAAC^Me)Cu(C₆Me₆)]⁺FAP⁻ (IIb) were evaluated for their catalytic performance and demonstrated high efficacy as copper(I) catalysts in the cycloaddition reaction of benzyl azide and various terminal alkynes, yielding 1,4-disubstituted 1,2,3-triazoles.¹³ These findings indicate that the phosphorane (C₂F₅)₃PF₂ exhibits sufficient Lewis acidity to abstract fluoride from transition metal complexes, thereby serving as a viable precursor for the synthesis of cationic transition metal species incorporating the FAP⁻ counteranion.¹ Herein, we report the reactivity of IIa and IIb with selected different Lewis bases, focusing on the synthesis and characterization of N-heterocyclic carbene (NHC)- and cyclic (Alkyl)(amino)carbene (cAAC)-ligated copper cations featuring the weakly coordinating FAP⁻ counteranion.

Results and discussion

The use of [(carbene)Cu(C₆Me₆)]⁺ as synthon for [(carbene)Cu]⁺

As our recent investigations already revealed that the hexamethylbenzene ligand of [(IDipp)Cu(C₆Me₆)]⁺FAP⁻ (IIa) can be exchanged easily by other 2 VE (valence electron) donors, such as THF,¹ we became interested in studying this behavior in more detail. Thus, we reacted IIa with selected nitrogen, oxygen, sulfur as well as phosphorus 2 VE donor ligands to probe their ability to replace C₆Me₆. Using this strategy, we isolated and fully characterized the copper FAP⁻ salts [(IDipp)Cu(LB)]⁺FAP⁻ (LB = NH₃, 1; C₆H₁₂N₂ = DABCO, 2; C₇H₁₀N₂ = DMAP, 3; C₄H₄N₂ = pyrazine, 4; C₁₃H₉N = acridine, 5; η¹-O=C₁₃H₉N = acridone, 6; C₄H₁₀S = SEt₂, 7; C₄H₈S = THT, 8; PCy₃, 9) as well as the dinuclear complex [{(IDipp)Cu}₂(C₂N₃H₃)₂]²⁺2FAP⁻ (10) (C₂N₃H₃ = 1,2,4-triazole). All reactions occur at room temperature in dichloromethane or chloroform in yields of 40–87% (Scheme 1).

Scheme 1 Synthesis of [(IDipp)Cu(LB)]⁺FAP⁻ (LB = NH₃, 1; C₆H₁₂N₂ = DABCO, 2; C₇H₁₀N₂ = DMAP, 3; C₄H₄N₂ = pyrazine, 4; C₁₃H₉N = acridine, 5; η¹-O=C₁₃H₉N = acridone, 6; C₄H₁₀S = SEt₂, 7; C₄H₈S = THT, 8; PCy₃, 9) (top) and [{(IDipp)Cu}₂(C₂N₃H₃)₂]²⁺2FAP⁻ (10, bottom, C₂N₃H₃ = 1,2,4, triazole) via substitution of hexamethylbenzene of [(IDipp)Cu(C₆Me₆)]⁺FAP⁻ (IIa).

The most straight forward probe to confirm the formation of the complexes presented in Scheme 1 is a shift of the methyl resonances of the coordinated hexamethylbenzene in the ¹H NMR spectra of the reaction mixtures. After work-up, the ¹H NMR signal of hexamethylbenzene is absent. In the ¹H NMR spectrum of [(IDipp)Cu(NH₃)]⁺FAP⁻ (1) the four iPr methyl groups of the Dipp ligand gave rise to two doublets at 1.24 and 1.25 ppm in CDCl₃ and the corresponding methine protons were observed as a septet at 2.49 ppm. The signals of both phenyl groups were split into doublets (CH_meta) and triplets (CH_para) and were detected at 7.34 and 7.56 ppm, respectively. Additionally, the signals of the olefinic protons of the backbone were observed at 7.24 ppm. Besides the typical signals of the NHC ligand, the three protons of the ammine ligand in 1 gave rise to a broad resonance at 2.05 ppm in CDCl₃, which is similar to δ(¹H) of [(IDipp)Cu(NH₃)][BF₄] with 2.26 ppm.¹⁴ There are neither significant differences in the ¹⁹F and ³¹P NMR spectra of the mer-FAP⁻ anion nor in the ¹H and ¹³C{¹H} NMR spectra of the IDipp ligand in any of these compounds. Likewise, there is no mentionable variation in the chemical shifts in dependence of whether nitrogen, sulfur or phosphorous binds towards the copper center. Table 1 summarizes selected chemical shifts of the ¹H and ¹³C{¹H} NMR spectra of the carbene ligand in the complex cations of [(IDipp)Cu(LB)]⁺FAP⁻.

Table 1 Selected ¹H and ¹³C{¹H} NMR chemical shifts [ppm] of the IDipp ligands of 1–10 in CDCl₃

	δ (^13C{^1H}) N–C–N	δ (^1H) aryl-CHpara	δ (^1H) aryl-CHmeta	δ (^1H) N–CH–CH–N	δ (^1H) iPr–CH	δ (^1H) iPr–CH3
1	177.5	7.56	7.34	7.24	2.49	1.24/1.25
2	176.6	7.56	7.34	7.28	2.44	1.21/1.26
3	178.3	7.57	7.36	7.29	2.55	1.24/1.27
4	177.2	7.60	7.35	7.29	2.51	1.07/1.25
5	177.5	7.57	7.54	7.50	2.67	1.17/1.33
6	177.9	7.59	7.38	7.31	2.62	1.26/1.28
7	176.2	7.56	7.35	7.32	2.50	1.22/1.27
8	176.3	7.58	7.36	7.32	2.49	1.21/1.27
9	178.0	7.53	7.34	7.32	2.54	1.24/1.26
10	181.8	7.65	7.35	7.23	2.52	0.94–1.06/1.22

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In addition to multinuclear NMR spectroscopy, the NHC copper FAP⁻ salts were characterized by using IR spectroscopy, HRMS, as well as elemental analysis (see ESI†). Furthermore, single crystals of 1, 3, 5, 6, 7, and 10 suitable for X-ray diffraction (XRD) were obtained (Fig. 1, 2 and Table 2). The central copper atom in the complexes 1, 3, 5, and 7 is linearly coordinated by the IDipp ligand and the nitrogen or sulfur atom of the neutral donor ligand with C1–Cu–N1 angles of 177.19(15)° (1), 175.45(9)° (3), and 179.62(7)° (5) and a C1–Cu–S angle of 176.49(8)° (7). Interestingly, the acridone ligand in 6 coordinates via the oxygen atom. The C1–Cu–O angle of 169.58(9)° is slightly distorted from a linear arrangement and the Cu–O distance amounts to 1.8313(16) Å. In 1, 3, 5, 6, and 7 the distances between the carbenic carbon atom and the copper atom are very close (<3σ) (1: 1.882(3) Å, 3: 1.875(2) Å, 5: 1.8789(18) Å, 6: 1.863(2) Å, 7: 1.887(3) Å) and similar to d(Cu–C) in other copper NHC complexes reported by Nolan et al. (1.884(2)–1.956(10) Å).¹⁵ The Cu–N1 bond distances in 1 (1.908(3) Å) and 5 (1.9038(15) Å) are slightly longer than d(Cu–N1) found in 3 (1.8785(19) Å), but within the standard range of precedent Cu–N bonds in NHC complexes.^16,17

Fig. 1 Molecular structures of the complex cations of [(IDipp)Cu(NH₃)]⁺FAP⁻ (1, top left), [(IDipp)Cu(C₇H₁₀N₂)]⁺FAP⁻ (3, top right), [(IDipp)Cu(C₁₃H₉N)]⁺FAP⁻ (5, middle left), [(IDipp)Cu(η¹-O=C₁₃H₉N)]⁺FAP⁻ (6, middle right) and [(IDipp)Cu(C₄H₁₀S)]⁺FAP⁻ (7, bottom) in the solid state (ellipsoids set at the 50% probability level; Dipp substituents are shown as wire-and-stick models). Hydrogen atoms (except the ones of NH₃ in 1) and co-crystallized solvent molecules in the crystal structures of 1, 3, and 6 are omitted for clarity. Only one of two independent molecules in the asymmetric unit of 1 and 3 are shown. Selected bond length and angles are given in Table 2 and Fig. S1–S5 in the ESI.†

Fig. 2 Molecular structure of the complex cation of [{(IDipp)Cu}₂(C₂N₃H₃)₂]²⁺2FAP⁻ (10) in the solid state (ellipsoids set at the 50% probability level; Dipp substituents are shown as wire-and-stick models). Hydrogen atoms except for the ones bound to N5 and N6 and a co-crystallized solvent molecule are omitted for clarity. Selected bond length and angles are collected in Table 2 and Fig. S6 in the ESI.†

Table 2 Selected bond lengths [Å] and angles [°] of the copper carbene-complexes 1, 3, 5, 6, 7, 10, 11, and 12

	Cu–C1	Cu–N/O/S	C1–Cu–N/O/S
1	1.882(3)	1.908(3)	177.19(15)
3	1.875(2)	1.8785(19)	175.45(9)
5	1.8789(18)	1.9038(15)	179.62(7)
6	1.863(2)	1.8313(16)	169.58(9)
7	1.887(3)	2.1705(8)	176.49(8)
10	1.937(6)	2.038(5)	128.50(19)
		2.035(4)	132.12(19)
11	1.900(4)	1.927(3)	176.68(15)
12	1.890(3)	1.906(2)	170.45(12)

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The Cu–S bond distance of the central copper atom to sulfur in 7 of 2.1705(8) Å is similar to values observed for [(IMes)Cu(SSi(iPr)₃)] (2.1336(4) Å) or [(IMes)Cu(SC(O)CH₃)] (2.1483(9) Å).¹⁸ The dinuclear complex 10 crystallizes in the monoclinic space group P2₁/m with one dinuclear dicationic complex [{(IDipp)Cu}₂(C₂N₃H₃)₂]²⁺, two mer-isomer FAP⁻ counteranions, and three solvent molecules in the unit cell. Thus, a crystallographically imposed mirror plane is located perpendicular through the atoms N5 and N6. The Cu–C1 distance of 1.937(6) Å is slightly longer than the distances observed in the related mononuclear compounds discussed before (Table 2). Both [(IDipp)Cu]⁺ moieties are bridged by two 1,2,4-triazole ligands with angles of C1–Cu1–N3 128.50(19)° and C1–Cu1–N4 132.12(19)°, respectively, and bond distances of 2.038(5) and 2.035(4) Å between Cu and N3 or N4. These distances are longer compared to d(Cu–N) in 1, 3, and 5 (1.88–1.91 Å) due to the higher steric demand and the increased coordination number at copper in 10.

As the hexamethylbenzene ligand in the IDipp complex IIa is easily replaced by various 2 VE donor ligands, we expanded our study to the related cAAC-ligated complex [(cAAC^Me)Cu(C₆Me₆)]⁺FAP⁻ (IIb). The reaction of IIb with DABCO or pyrazine resulted in the formation of dinuclear complexes [{(cAAC^Me)Cu}₂(C₆H₁₂N₂)]²⁺2FAP⁻ (11) and [{(cAAC^Me)Cu}₂ (C₄H₄N₂)]²⁺2FAP⁻ (12) in 62% (11) and 68% (12) yield, respectively. The reaction of IIb with DMAP or SEt₂ afforded the mononuclear complexes [(cAAC^Me)Cu(C₇H₁₀N₂)]⁺FAP⁻ (13) and[(cAAC^Me)Cu(C₄H₁₀S)]⁺FAP⁻ (14) in 57% (13) and 74% (14) yield (Scheme 2).

Scheme 2 Synthesis of [{(cAAC^Me)Cu}₂(C₆H₁₂N₂)]²⁺2FAP⁻ (11), [{(cAAC^Me)Cu}₂(C₄H₄N₂)]²⁺2FAP⁻ (12), [(cAAC^Me)Cu(C₇H₁₀N₂)]⁺FAP⁻ (13), and [(cAAC^Me)Cu(C₄H₁₀S)]⁺FAP⁻ (14) via hexamethylbenzene substitution of [(cAAC^Me)Cu(C₆Me₆)]⁺FAP⁻ (IIb).

The complexes 11–14 were characterized by multinuclear NMR spectroscopy, elemental analysis, IR spectroscopy, and HRMS (13, 14). In analogy to the IDipp copper complexes 1–10 introduced above, the ¹⁹F and ³¹P NMR chemical shifts of mer-FAP⁻ and the ¹H and ¹³C{¹H} chemical shifts of the cAAC^Me ligand of these compounds did not reveal significant differences. In case of 11 and 12, the signals for the carbene ligand were observed with a relative intensity of 2 with respect to the signals of DABCO or pyrazine. These findings match the results of the elemental analysis and X-ray diffraction, which are in accordance with dinuclear structures in solution and in the solid state. Single crystals of 11 and 12 suitable for XRD were obtained by diffusion of n-hexane into solutions of 11 or 12 in dichloromethane (Fig. 3 and Table 2). Both complexes 11 and 12 crystallize in the monoclinic space group P2₁/n and are located on an inversion center. Besides the coordination of the carbene ligand, the copper atom is coordinated to the nitrogen atom N1 of the DABCO or pyrazine ligand, respectively, with almost linear C1–Cu–N1 angles of 176.68(15)° (11) and 170.45(12)° (12). A comparison of both closely related structures shows that the Cu–C1 bond lengths (11: 1.900(4) Å; 12: 1.890(3) Å) and the Cu–N1 distances (11: 1.927(3) Å; 12: 1.906(2) Å) differ only marginally.

Fig. 3 Molecular structures of the complex cations of [{(cAAC^Me)Cu}₂{C₆H₁₂N₂}]²⁺2FAP⁻ (11; left) and [{(cAAC^Me)Cu}₂{C₄H₄N₂}]²⁺2FAP⁻ (12; right) in the solid state (ellipsoids set at the 50% probability level; Dipp ligands are shown as wire-and-stick models). Hydrogen atoms are omitted for clarity. Selected bond length and angles are collected in Table 2 and Fig. S7, S8 in the ESI.†

Fluoride abstraction in the presence of neutral N- and O-donor ligands

Previous studies demonstrated that the percent buried volume model (%V_Bur), developed by Cavallo and colleagues, serves as a powerful descriptor for evaluating the steric properties of N-heterocyclic carbenes, phosphines, and related ligands in transition metal chemistry.¹⁹ Building on this approach, we introduced the LAB-Rep model, designed to assess steric repulsion between specific Lewis acid and base pairs.¹⁰ According to this model, the favored mer-trans isomer of (C₂F₅)₃PF₂–LB, with a percent buried volume of 67.7%V_bur, is considered to be very bulky, rendering the formation of LA/LB adducts with sterically hindered Lewis bases unlikely. Building on our previous studies,¹ we employed the phosphorane (C₂F₅)₃PF₂ for the fluoride abstraction from fluoride complexes [(carbene)CuF], featuring IDipp, SIDipp, and cAAC^Me as carbene ligands, in the presence of a nucleophile. In the following we explore the question whether (C₂F₅)₃PF₂ can assist fluoride exchange reactions in complexes [(carbene)CuF] with 2 VE ligands, or if (i) a replacement of the neutral carbene ligand with the 2 VE ligand or (ii) the formation of Lewis acid/base pair of the 2 VE ligand and (C₂F₅)₃PF₂ prevails.

The reaction of [(cAAC^Me)CuF] (Ic) with (C₂F₅)₃PF₂ in a solvent mixture of acetonitrile and dichloromethane afforded the acetonitrile adduct [(cAAC^Me)Cu(N≡CMe)]⁺FAP⁻ (15), whereas the reaction of [(IDipp)CuF] (Ia) under similar conditions led to the three-coordinated complex [(IDipp)Cu(N≡CMe)₂]⁺FAP⁻ (16) (Scheme 3). This observation may seem contradictory to the assumption of the LAB-Rep model, as acetonitrile is considered a sterically non-demanding LB, and the formation of a phosphorane-acetonitrile adduct would be expected. However, the pronounced fluoride ion affinity of the phosphorane (405.5 kJ mol⁻¹)¹ seemingly favors fluoride abstraction over adduct formation, thus leading to the generation of [(IDipp)Cu(N≡CMe)₂]⁺ and the weakly coordinating FAP⁻ anion.

The sterically more demanding benzonitrile yielded the di-coordinated copper(I) complex [(IDipp)Cu(N≡CPh)]⁺FAP⁻ (17). All reactions proceeded in good yields of 69% (15), 81% (16) and 82% (17), respectively (Scheme 3). Compounds 15–17 were fully characterized by ¹H, ¹³C{¹H}, ¹⁹F, and ³¹P NMR spectroscopy, IR spectroscopy, HRMS, and elemental analysis. The ¹⁹F and ³¹P NMR spectra confirm the formation of the mer-isomer of the FAP⁻ anion, consistent with other previously reported FAP⁻ complex salts.^1,20

Scheme 3 Synthesis of [(carbene)Cu(LB)]⁺FAP⁻ complexes 15–17via fluoride ion abstraction from [(carbene)CuF] using (C₂F₅)₃PF₂ in the presence of N-donor ligands.

The IR spectrum of 17 displays a characteristic band at 2275 cm⁻¹ for the N≡C stretching vibration, which is shifted 40 cm⁻¹ to higher wavenumbers compared to non-coordinated benzonitrile (2234 cm⁻¹).²¹ This shift can be rationalized by coordination to a Lewis-acidic center in conjunction with negligible π-back-bonding from copper to benzonitrile. Significant π-back-bonding would lead to a decrease in [small nu, Greek, tilde](C≡N). Higher wavenumbers for the C≡N stretch have been reported for other end-on coordinated Cu(I) complexes, previously.²² We discussed these phenomena for other cationic copper complexes previously. For example, the related complex [(IDipp)Cu(PhC≡CPh)]⁺FAP⁻ shows a lack of π-back-bonding from the cationic [(IDipp)Cu]⁺ complex fragment to the alkyne, which was evident from very similar δ(¹³C) shifts of the C≡C unit of the free and coordinated alkyne (Δδ_alkyne ∼0.5 ppm), which indicates a rather weak copper–alkyne interaction.¹³

Single crystals suitable for XRD were obtained for compounds 16 and 17, and selected bonding parameters of the molecular structures (Fig. 4) are summarized in Table 3. The cationic complex [(IDipp)Cu(N≡CMe)₂]⁺ in 16 exhibits a distorted trigonal-planar geometry at the metal atom with angels of 121.11(9)° (C1–Cu–N1), 131.08(10)° (C1–Cu–N2), and 107.71(9)° (N1–Cu–N2). In contrast, the copper atom in 17 adopts a linear environment with a C1–Cu–N1 angle of 178.03(7)°. Due to the reduced coordination number of copper in 17, the Cu–N1 distance of 1.8453(14) Å is significantly shorter than those observed in the tri-coordinated complex 16 (1.967(2) and 1.938(2) Å). The Cu–C1 bond length, however, is less sensitive to the coordination number, with 1.909(2) and 1.8848(15) Å in 16 and 17, respectively.

Fig. 4 Molecular structures of the complex cations of [(IDipp)Cu(N≡CMe)₂]⁺FAP⁻ (16; left) and [(IDipp)Cu(N≡CPh)]⁺FAP⁻ (17; right) in the solid state (ellipsoids set at the 50% probability level; Dipp substituents are shown as wire-and-stick models). Hydrogen atoms are omitted for clarity. Selected bond lengths and angles are collected in Table 3 and Fig. S9, S10 in the ESI.†

Table 3 Selected bond lengths [Å] and angles [°] of the copper carbene-complexes 16, 17, 19–21, 23, 24, 26, and 27

	Cu–C1	N/O	C1–Cu–N/O
16	1.909(2)	1.967(2)	121.11(9)
		1.938(2)	131.08(10)
17	1.8848(15)	1.8453(14)	178.03(7)
19	1.893(3)	1.935(3)	171.88(13)
20	1.882(3)	1.942(3)	175.47(12)
21	1.8716(17)	1.9492(15)	175.97(7)
23	1.8853(17)	1.9038(15)	174.25(6)
24	1.878(2)	1.916(2)	172.2(1)
26	1.873(3)	2.054(2)	142.16(11)
	1.876(3)	2.027(2)	145.85(11)
			144.71(12)
			143.59(11)
27	1.866(3)	1.8624(19)	167.61(9)

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Additionally, we explored the reaction of fluoride complexes Ia with (C₂F₅)₃PF₂ in the presence of aniline, and for Ic, with (C₂F₅)₃PF₂ in the presence of diphenylamine and the cationic copper complexes [(carbene)Cu(NH₂Ph)]⁺FAP⁻ (carbene = IDipp, 18; SIDipp, 19; cAAC^Me, 20) and [(IDipp)Cu(NHPh₂)]⁺FAP⁻ (21) were isolated in moderate to good yields (Scheme 4). The ¹H NMR spectra of complexes 18–21 show characteristic broad singlets for the NH protons (18: 4.74 ppm, 19: 4.24 ppm, 20: 4.58 ppm, 21: 6.36 ppm), compared to free aniline (3.69 ppm)²³ and diphenylamine (5.69 ppm).²⁴ Further characterization was carried out using NMR and IR spectroscopy, HRMS and elemental analysis. SC-XRD confirmed the molecular structures of 19–21 (Fig. 5 and Table 3). The complex cations adopt linear structures in which copper is coordinated by both the carbene and the amino ligand, with C1–Cu–N1 angles of 171.88(13)° (19), 175.47(12)° (20), and 175.97(7)° (21). In 19 and 20, the Cu–N1 bond length (19: 1.935(3) Å; 20: 1.942(3) Å) is significantly shorter than d(Cu–N) reported for related aniline complexes [(dtbpe)Cu(NH₂Ph)]⁺[BF₄]⁻ (2.010(2) Å; dtbpe = 1,2-bis(di-tertbutyl-phosphino)ethane)²⁵ and [(JohnPhos)Cu (NH₂Ph)][PF₆] (1.964(2) Å; JohnPhos = 2-(di-tertbutyl-phosphino)-1,1′-biphenyle).²⁶

Scheme 4 Synthesis of [(carbene)Cu(LB)]⁺FAP⁻ complexes 18–20via fluoride ion abstraction from [(carbene)CuF] using (C₂F₅)₃PF₂ in the presence of amines.

Fig. 5 Molecular structures of the complex cations of [(SIDipp)Cu(NH₂Ph)]⁺FAP⁻ (19, left), [(cAAC^Me)Cu(NH₂Ph)]⁺FAP⁻ (20, middle) and [(IDipp)Cu(NHPh₂)]⁺FAP⁻ (21, right) in the solid state (ellipsoids set at the 50% probability level; Dipp substituents are shown as wire-and-stick models). Hydrogen atoms except for those of the N atom of the aniline and diphenylamine ligands and a solvent molecule in the crystal structure of 19 are omitted for clarity. Only one of two independent cations in the asymmetric unit of 19 is shown. Selected bond lengths and angles are collected in Table 2 and Fig. S11–S13 in the ESI.†

This difference may be attributed to the lower coordination number of copper in 19 and 20. The Cu–C1 distances in 19 (1.893(3) Å) and 20 (1.882(3) Å) are nearly identical within experimental error. Compound 21 displays slightly different bond lengths (Cu–N1: 1.9492(15) Å, Cu–C1: 1.8716(17) Å).

Moreover, the reactivity of the fluoride complexes [(IDipp)CuF] (Ia) and [(cAAC^Me)CuF] (Ic) towards (C₂F₅)₃PF₂ in the presence of one equivalent of pyridine or fluorinated pyridine derivates was investigated. Fluoride abstraction followed by pyridine coordination led to isolation and full characterization of the cationic complexes [(IDipp)Cu(NC₅H₅)]⁺FAP⁻ (22), [(cAAC^Me)Cu(NC₅H₅)]⁺FAP⁻ (23), [(IDipp)Cu(NC₅H₃F₂)]⁺FAP⁻ (24), and [(IDipp)Cu(NC₅H₂F₃)]⁺FAP⁻ (25) in yields of 68–80% (Scheme 5). The reaction of the highly fluorinated 2,3,5,6-tetrafluoropyridine with Ia in the presence of (C₂F₅)₃PF₂ did not result in [(IDipp)Cu(NC₅HF₄)]⁺FAP⁻ but [{(IDipp)Cu}₂]²⁺2FAP⁻ was obtained. The low basicity and thus poor coordination ability of tetrafluoropyridine favors the coordination of the IDipp substituent of the carbene ligand, resulting in the dimeric dicationic complex [{(IDipp)Cu}₂]²⁺.¹ The formation of 22–25 was confirmed by ¹H, ¹³C{¹H}, ¹⁹F, and ³¹P NMR spectroscopy. A decreasing resonance frequency of the hydrogen and carbon nuclei in meta-position of pyridine with an increasing number of fluorine substituents was observed (δ(¹H): 22: 7.77/7.50 ppm, 24: 7.03 ppm; 25: 6.75 ppm; δ(¹³C): 22: 147.5/126.8 ppm; 24: 108.3 ppm; 25: 98.1 ppm). In addition, single crystals of 23 and 24 suitable for XRD studies were obtained (Fig. 6).

Scheme 5 Synthesis of [(carbene)Cu(LB)]⁺FAP⁻ complexes 22–25via fluoride ion abstraction from [(carbene)CuF] using (C₂F₅)₃PF₂ in the presence of (partially fluorinated) pyridine.

Fig. 6 Molecular structures of the complex cations of [(cAAC^Me)Cu(NC₅H₅)]⁺FAP⁻ (23; left) and [(IDipp)Cu(NC₅H₃F₂)]⁺FAP⁻ (24; right) in the solid state (ellipsoids set at the 50% probability level; Dipp substituents are shown as wire-and-stick models). Hydrogen atoms are omitted for clarity. Selected bond lengths and angles are collected in Table 3 and Fig. S14, S15 in the ESI.†

The solid-state structures of 23 and 24 confirm the coordination of pyridine and the linear geometry at copper, with C1–Cu–N1 angles of 174.25(6)° (23) and 172.2(1)° (24). The Cu–C1 distances in 23 (1.8853(17) Å) and 24 (1.878(2) Å) are within the typical range compared to related complexes.^13,27 In contrast, the Cu–N1 bond in 23 (1.9038(15) Å) is slightly shorter than in 24 (1.916(2) Å), which mirrors the reduced basicity of 2,6-difluoropyridine relative to pyridine. The Cu–C1 and Cu–N1 bond lengths in 23 are slightly longer than those reported by Steffen et al. for the related pyridine complex [(IDipp)Cu(NC₅H₅)][BF₄] (Cu–C1: 1.872(2) Å; Cu–N1: 1.8900(18) Å).²⁷

The stabilization of the carbene copper cations [(IDipp)Cu]⁺ by oxygen donor ligands is demonstrated by the formation of [{(IDipp)Cu(μ-ONC₅H₅)}₂]²⁺2FAP⁻ (26), [(IDipp)Cu(η¹O=CPh₂)]⁺FAP⁻ (27), and [(cAAC^Me)Cu(THF)]⁺FAP⁻ (28) depicted in Scheme 6. Fluoride abstraction from [(IDipp)CuF] (Ia) with (C₂F₅)₃PF₂ in the presence of pyridine-N-oxide yielded the dinuclear pyridine-N-oxide-bridged complex 26 in 81% yield. The reaction of Ia with (C₂F₅)₃PF₂ in the presence of benzophenone afforded the mononuclear complex 27 in 79% yield and the reaction of [(cAAC^Me)CuF] (Ic) with the phosphorane in Et₂O/THF afforded 28 in 68% yield. The ¹H NMR analysis of 26 revealed broadening of the pyridine-N-oxide resonances at room temperature. However, at −36.5 °C, three well resolved resonances were observed at 7.71 (pyridine-aryl-C_paraH), 7.47 (pyridine-aryl-C_orthoH), and 7.38 ppm (pyridine-aryl-C_metaH) (see Fig. S118 in the ESI†). SC-XRD confirmed the dinuclear structure of 26 in the solid state, revealing a central Cu₂O₂ core, in which two [(IDipp)Cu]⁺ cations are bridged by two pyridine-N-oxide ligands (Fig. 7). These extended bond distances indicate the absence of significant Cu⋯Cu bonding interactions. The Cu–O–Cu angles in 26 are 108.47(11)° and 107.84(10)°, respectively. The benzophenone ligand in [(IDipp)Cu(η¹-O=CPh₂)]⁺FAP⁻ (27) adopts an end-on η¹-coordination mode in the solid state and in solution. Such a shift in δ(¹³C) is a hallmark of benzophenone ligands coordinated via the oxygen atom in an end-on η¹-fashion.²⁸

Scheme 6 Synthesis of complexes 26–28via fluoride ion abstraction from [(carbene)CuF] using (C₂F₅)₃PF₂ in the presence of O-donor ligands.

Fig. 7 Molecular structures of the complex cations of [{(IDipp)Cu(μ-ONC₅H₅)}₂]²⁺2FAP⁻ (26; left) and [(IDipp)Cu(η¹-O=CPh₂)]⁺FAP⁻ (27; right) in the solid state (ellipsoids set at the 50% probability level; Dipp substituents are shown as wire-and-stick models). Hydrogen atoms and two co-crystallized solvent molecules in the crystal structure of 26 are omitted for clarity. Selected bond lengths and angles are collected in Table 3 and Fig. S16, S17 in the ESI.†

In contrast, a side-on η²-coordination of the O=C moiety would induce a shift to lower resonance frequency,^29,30 as previously observed for the nickel complexes [(NHC)₂Ni(η²-O=CPh₂)] (NHC = IiPr, IMes) which we have reported earlier.³⁰ In these nickel complexes, the [(NHC)₂Ni] unit exhibits strong π-back-donation, favoring side-on coordination. SC-XRD experiments of 27 further confirm the end-on η¹-coordination mode in the solid state (Fig. 7). The η¹-hapticity of the oxygen atom suggests minimal or no π-back-donation from the [(IDipp)Cu]⁺ cation, which is consistent with the contracted and energetically low-lying d-orbitals characteristic for the closed-shell copper(I) center. The O–C2 bond length in 27 (1.246(3) Å) remains nearly unchanged compared to free benzophenone (cf. distances of benzophenone: 1.23(1) Å),³¹ indicating negligible electron density donation from copper to the carbonyl moiety. The Cu–O bond distance of 1.8624(19) Å is slightly longer than those observed in the alkoxide complexes [(IDipp)Cu(OX)] (X = Et: 1.799(3) Å;¹⁶tBu: 1.8104(13) Å;³² CH(Me)Ph: 1.794(3) Å (ref. 33)) or carboxylato complexes [(IDipp)Cu(OX)] (X = C(=O)H: 1.848(2) Å;³⁴ C(=O)Me:1.850(3) Å (ref. 35)), as expected for a ketone ligand. The Cu–O–C2 bond angle of 133.48(18)° is consistent with oxygen lone-pair coordination to the [(IDipp)Cu]⁺ center.

Conclusions

Ligand exchange reactions of [(IDipp)Cu(C₆Me₆)]⁺FAP⁻ (IIa) were studied in some detail leading to the copper FAP⁻ salts [(IDipp)Cu(LB)]⁺FAP⁻ (LB = NH₃, 1; C₆H₁₂N₂ = DABCO, 2; C₇H₁₀N₂ = DMAP, 3; C₄H₄N₂ = pyrazine, 4; C₁₃H₉N = acridine, 5; η¹-O=C₁₃H₉N = acridone, 6; C₄H₁₀S = SEt₂, 7; C₄H₈S = THT, 8; PCy₃, 9) as well as the dinuclear 1,2,4-triazole complex [{(IDipp)Cu}₂(C₂N₃H₃)₂]²⁺2FAP⁻ (10). Similarly, [(cAAC^Me)Cu(C₆Me₆)]⁺FAP⁻ (IIb) was used for the synthesis of [(cAAC^Me)Cu(LB)]⁺FAP⁻ (LB = C₇H₁₀N₂, 13; C₄H₁₀S, 14) via replacement of the C₆Me₆ ligand. The reactions of DABCO or pyrazine with IIa afforded [{(cAAC^Me)Cu}₂(C₆H₁₂N₂)]²⁺2FAP⁻ (11) and [{(cAAC^Me)Cu}₂(C₄H₄N₂)]²⁺2FAP⁻ (12). In all cases the cationic copper(I) complexes [(carbene)Cu(LB)]⁺ were stabilized by the weakly coordinating tris(pentafluoroethyl)trifluorophosphate anion (FAP⁻ anion, [(C₂F₅)₃PF₃]⁻). Furthermore, we extended the use of the readily available Lewis acid tris(pentafluoroethyl)difluorophosphorane (C₂F₅)₃PF₂ as fluoride abstraction reagent for the generation of cationic copper(I) complexes. The reactions of (C₂F₅)₃PF₂ with [(IDipp)CuF] (Ia), [(SIDipp)CuF] (Ib), or [(cAAC^Me)CuF] (Ic) in the presence of different Lewis bases (LB), i.e. nitriles, amines, fluorinated and non-fluorinated pyridines, and oxygen donor ligands, were studied. The complex salts [(IDipp)Cu(LB)]⁺FAP⁻ (LB = (N≡CMe)₂, 16; N≡CPh, 17; NH₂Ph, 18; NHPh₂, 21; NC₅H₅, 22; NC₅H₃F₂, 24; NC₅H₂F₃, 25; η¹-O=CPh₂, 27), [(SIDipp) Cu(NH₂Ph)]⁺FAP⁻ (19), and [(cAAC^Me)Cu(LB)]⁺FAP⁻ (LB = N≡CMe, 15; NH₂Ph, 20; NC₅H₅, 23; THF, 28) were isolated and characterized. In addition, the dinuclear complex [{(IDipp)Cu(μ-ONC₅H₅)}₂]²⁺2FAP⁻ (26) was isolated. This approach was investigated for different 2 VE nitrogen and oxygen donor ligands. In none of these cases the carbene ligand was replaced with the 2 VE ligand employed, the formation of Lewis acid/base pair of the 2 VE ligand and (C₂F₅)₃PF₂ was never observed in the presence of the copper fluoride, and the FAP⁻ anion coordinated in none of these cases to the copper cations. Hence, mixtures of [(carbene)CuF] and (C₂F₅)₃PF₂ serve as synthon for [(carbene)Cu]⁺.

Experimental

General considerations

All reactions and subsequent manipulations involving organometallic reagents were carried out under an argon atmosphere by using standard Schlenk techniques or in a Glovebox (Innovative Technology Inc., and MBraun Uni Lab).³⁶ All reactions were performed in oven-dried glassware. Elemental analyses were performed in the microanalytical laboratory of the Institute of Inorganic Chemistry of the University Würzburg with an Elementar vario micro cube. High-resolution mass spectroscopy (HRMS) was performed on a Thermo Scientific Exactive Plus mass spectrometer, equipped with an Orbitrap Mass Analyzer. NMR spectra were recorded on a Bruker Avance 400 (¹H, 400.1 MHz; ¹³C, 100.6 MHz; ¹⁹F, 376.8 MHz; ³¹P, 162.0 MHz), a Bruker Avance 500 (¹H, 500.1 MHz; ¹³C, 125.8 MHz; ¹⁹F, 470.5 MHz; ³¹P, 202.4 MHz) and a Bruker Avance 600 (¹H, 600.2 MHz; ¹³C, 150.9 MHz; ¹⁹F, 564.7 MHz; ³¹P, 242.9 MHz) spectrometer using CD₂Cl₂ or CDCl₃ as solvent. Assignment of the ¹H NMR and ¹³C{¹H} NMR data was supported by ¹H, ¹H and ¹³C{¹H},¹H correlation experiments. ¹³C NMR spectra were recorded broad-band proton-decoupled (¹³C{¹H}) at 298 K, if not otherwise noted. Chemical shifts are listed in parts per million (ppm), reported relative to TMS and were calibrated against residual solvent signals (δ(¹H): CDHCl₂ 5.32, CHCl₃ 7.26; δ(¹³C): CD₂Cl₂ 53.84, CDCl₃ 77.16)³⁷ or external CFCl₃ (δ(¹⁹F): 0) and 85% H₃PO₄ (δ(³¹P): 0). If not otherwise noted ¹⁹F and ³¹P NMR spectra were not proton decoupled. Coupling constants are quoted in Hertz. Infrared spectra were recorded under an argon atmosphere on solid samples on a Bruker Alpha FT-IR spectrometer by using an ATR unit at room temperature. Values are given in cm⁻¹. All solvents for synthetic reactions were HPLC grade, further treated to remove traces of water using an Innovative Technology Inc. Pure-Solv Solvent Purification System. CD₂Cl₂ and CDCl₃ were purchased from Sigma-Aldrich and stored over molecular sieve. The compounds [(IDipp)CuF] (Ia),³⁸ [(SIDipp)CuF] (Ib),¹³ [(cAAC^Me)CuF] (Ic),¹³ [(IDipp)Cu(C₆Me₆)]⁺FAP⁻ (IIa)¹ and [(cAAC^Me)Cu(C₆Me₆)]⁺FAP⁻ (IIb)¹³ were prepared according to literature procedures. Commercially available (C₂F₅)₃PF₂ was used or the phosphorane was synthesized via electrochemical fluorination (ECF) starting from triethyl phosphine as reported in the literature.³⁹ All other starting materials were purchased from commercial sources and used without further purification.

Preparation of compounds

[(IDipp)Cu(NH₃)]⁺FAP⁻ (1). At room temperature and under atmospheric pressure anhydrous gaseous NH₃ was passed through a solution of IIa (100 mg, 94.4 μmol) in CHCl₃ (15 mL) over a period of 1 h. The reaction mixture was stirred for another 2 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 10 mL) and dried in vacuo to yield 1 (50 mg, 54.7 μmol, 58%) as a colorless solid. Single crystals of 1 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 1 in chloroform. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.24 (d, 12 H, ³J_HH = 7.0 Hz, iPr–CH₃), 1.25 (d, 12 H, ³J_HH = 7.0 Hz, iPr–CH₃), 2.05 (s_br, 3 H, NH₃), 2.49 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 7.24 (s, 2 H, N–CH–CH–N), 7.34 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.56 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 24.0 (iPr–CH₃), 25.0 (iPr–CH₃), 28.9 (iPr–CH), 124.1 (N–CH–CH–N), 124.7 (IDipp-aryl-C_meta), 131.4 (IDipp-aryl-C_para), 133.8 (IDipp-aryl-C_ipso), 145.5 (IDipp-aryl-C_ortho), 177.5 (N–C–N); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −44.9 (dm, 1 F, ¹J_PF = 888 Hz, PF), −80.3 (m, 3 F, CF₃), −81.9 (m, 6 F, CF₃), −88.8 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −115.8 (dm, 2 F, ²J_PF = 85 Hz, CF₂), −116.2 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −146.6 (tdm, ¹J_PF = 903 Hz, ¹J_PF = 888 Hz); IR ([cm⁻¹]): 3370 (w), 3300 (w), 3174 (vw), 3074 (vw), 2967 (s), 2929 (m), 2875 (m), 1666 (w), 1594 (w), 1551 (w), 1469 (m), 1413 (w), 1388 (w), 1366 (w), 1295 (m), 1271 (m), 1212 (s), 1183 (s), 1140 (s), 1126 (s), 1099 (s), 1060 (m), 963 (m), 936 (w), 875 (vw), 862 (vw), 804 (m), 759 (m), 724 (m), 706 (m), 673 (m), 618 (vs), 581 (m), 533 (m), 504 (w), 494 (m), 466 (w), 439 (m), 430 (m); HRMS (ESI) m/z [M]⁺ calcd for C₂₇H₃₉CuN₃: 468.2440, found: 468.2427; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9447; elemental analysis calcd (%) for C₃₃H₃₉CuF₁₈N₃P: C 43.36, H 4.30, N 4.60; found: C 43.35, H 4.01, N 4.73.

[(IDipp)Cu(C₆H₁₂N₂)]⁺FAP⁻ (2). A solution of IIa (100 mg, 94.4 μmol) and DABCO (10.6 mg, 94.4 μmol) in dichloro methane (5 mL) was stirred for 6 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (7 mL) and product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 2 (62.0 mg, 61.4 μmol, 65%) as a colorless solid. ¹H NMR (400.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.21 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.26 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 2.44 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 2.66 (s, 12 H, DABCO–CH₂), 7.28 (s, 2 H, N–CH–CH–N), 7.34 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.56 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH); ¹³C{¹H} NMR (100.6 MHz, CDCl₃, 298 K): δ [ppm] = 23.7 (iPr–CH₃), 25.3 (iPr–CH₃), 28.9 (iPr–CH), 124.3 (N–CH–CH–N), 124.7 (IDipp-aryl-C_meta), 131.5 (IDipp-aryl-C_para), 133.7 (IDipp-aryl-C_ipso), 145.6 (IDipp-aryl-C_ortho), 176.6 (N–C–N); the signal for the DABCO–CH₂-group was not detected; ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.3 (dm, 1 F, ¹J_PF = 891 Hz, PF), −80.2 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.5 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 83 Hz, CF₂), −116.4 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.3 (tdm, ¹J_PF = 903 Hz, ¹J_PF = 891 Hz); IR ([cm⁻¹]): 3172 (vw), 3144 (vw), 3073 (vw), 2957 (m), 2928 (w), 2875 (w), 1593 (vw), 1568 (vw), 1552 (vw), 1463 (m), 1415 (w), 1387 (w), 1367 (w), 1350 (vw), 1311 (m), 1295 (m), 1273 (vw), 1258 (vw), 1211 (vs), 1179 (s), 1140 (s), 1125 (s), 1099 (s), 1058 (m), 1015 (w), 973 (m), 962 (m), 937 (w), 905 (vw), 809 (s), 761 (m), 746 (w), 723 (m), 700 (w), 636 (w), 618 (s), 581 (w), 533 (w), 505 (vw), 495 (w), 439 (w), 429 (w); HRMS (ESI) m/z [M]⁺ calcd for C₃₃H₄₈CuN₄: 563.3175, found: 563.3159; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9446; elemental analysis calcd (%) for C₃₉H₄₈CuF₁₈N₄P: C 46.41, H 4.79, N 5.55; found: C 46.05, H 4.31, N 5.40.

[(IDipp)Cu(C₇H₁₀N₂)]⁺FAP⁻ (3). A solution of IIa (150 mg, 142 μmol) and DMAP (17.3 mg, 142 μmol) in dichloro methane (5 mL) was stirred for 3 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 3 (106 mg, 104 μmol, 73%) as a colorless solid. Single crystals of 3 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 3 in chloroform. ¹H NMR (400.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.24 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.27 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 2.55 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 2.93 (s_br, 6 H, DMAP–CH₃), 6.36 (s_br, 2 H, DMAP-aryl-C_metaH), 7.17 (s_br, 2 H, DMAP-aryl-C_orthoH), 7.29 (s, 2 H, N–CH–CH–N), 7.36 (d, 4 H, ³J_HH = 7.9 Hz, IDipp-aryl-C_metaH), 7.57 (t, 2 H, ³J_HH = 7.9 Hz, IDipp-aryl-C_paraH); ¹³C{¹H} NMR (100.6 MHz, CDCl₃, 298 K): δ [ppm] = 23.8 (iPr–CH₃), 25.1 (iPr–CH₃), 28.9 (iPr–CH), 39.4 (DMAP–CH₃), 124.2 (N–CH–CH–N), 124.6 (IDipp-aryl-C_meta), 131.3 (IDipp-aryl-C_para), 134.1 (IDipp-aryl-C_ipso), 145.8 (IDipp-aryl-C_ortho), 178.3 (N–C–N); the signals for the DMAP-aryl-C_ortho, DMAP-aryl-C_meta and DMAP-aryl-C_ipso carbon atoms were not detected; ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.3 (dm, 1 F, ¹J_PF = 893 Hz, PF), −80.2 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 81 Hz, CF₂), −116.5 (dm, 4 F, ²J_PF = 94 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.3 (tdm, ¹J_PF = 903 Hz, ¹J_PF = 893 Hz); IR ([cm⁻¹]): 3172 (vw), 3146 (vw), 3076 (vw), 2963 (m), 2952 (m), 2924 (w), 2876 (w), 2865 (w), 1715 (vw), 1623 (s), 1549 (m), 1464 (m), 1447 (m), 1410 (w), 1397 (w), 1365 (w), 1347 (w), 1313 (w), 1296 (m), 1256 (vw), 1213 (vs), 1178 (vs), 1125 (s), 1098 (s), 1075 (m), 1029 (m), 971 (m), 949 (w), 936 (w), 885 (vw), 832 (vw), 805 (s), 761 (m), 740 (w), 728 (m), 699 (w), 661 (vw), 637 (w), 618 (s), 581 (m), 549 (w), 530 (m), 505 (w), 494 (m), 438 (m), 429 (m); HRMS (ESI) m/z [M]⁺ calcd for C₃₄H₄₆CuN₄: 573.3019, found: 573.3002; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9437; elemental analysis calcd (%) for C₄₀H₄₆CuF₁₈N₄P: C 47.13, H 4.55, N 5.50; found: C 47.64, H 4.12, N 5.83.

[(IDipp)Cu(C₄H₄N₂)]⁺FAP⁻ (4). A solution of IIa (150 mg, 142 μmol) and pyrazine (11.3 mg, 142 μmol) in dichloro methane (5 mL) was stirred for 2 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 4 (108 mg, 110 μmol, 78%) as a yellow solid. ¹H NMR (400.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.07 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.25 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 2.51 (sept, 4 H, ³J_HH = 6.8 Hz, iPr–CH), 7.29 (s, 2 H, N–CH–CH–N), 7.35 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.60 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH), 7.93 (s, 4 H, pyrazine-aryl-CH); ¹³C{¹H} NMR (100.6 MHz, CDCl₃, 298 K): δ [ppm] = 23.8 (iPr–CH₃), 24.8 (iPr–CH₃), 28.9 (iPr–CH), 124.1 (N–CH–CH–N), 124.8 (IDipp-aryl-C_meta), 131.3 (IDipp-aryl-C_para), 134.6 (IDipp-aryl-C_ipso), 145.3 (IDipp-aryl-C_ortho), 145.9 (pyrazine-aryl-CH), 177.2 (N–C–N); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −44.9 (dm, 1 F, ¹J_PF = 889 Hz, PF), −80.2 (m, 3 F, CF₃), −81.9 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −115.8 (dm, 2 F, ²J_PF = 80 Hz, CF₂), −116.3 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.2 (tdm, ¹J_PF = 904 Hz, ¹J_PF = 890 Hz); IR ([cm⁻¹]): 3166 (vw), 3139 (vw), 3082 (vw), 2967 (m), 2929 (w), 2874 (w), 1591 (vw), 1554 (vw), 1468 (m), 1419 (m), 1388 (w), 1366 (w), 1294 (m), 1212 (vs), 1180 (s), 1136 (s), 1124 (s), 1098 (s), 1070 (m), 1060 (m), 1042 (w), 961 (m), 936 (w), 864 (vw), 805 (s), 759 (s), 721 (s), 637 (w), 618 (s), 580 (m), 549 (w), 533 (m), 505 (w), 494 (m), 458 (m), 437 (w), 429 (w); HRMS (ESI) m/z [M]⁺ calcd for C₃₁H₄₀CuN₄: 531.2549, found: 531.2533; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9445; elemental analysis calcd (%) for C₃₇H₄₀CuF₁₈N₄P: C 45.48, H 4.13, N 5.73; found: C 46.08, H 4.23, N 5.47.

[(IDipp)Cu(C₁₃H₉N)]⁺FAP⁻ (5). A solution of IIa (100 mg, 94.4 μmol) and acridine (16.9 mg, 94.4 μmol) in dichloro methane (5 mL) was stirred for 4 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 5 (84 mg, 78.0 μmol, 83%) as a yellow solid. Single crystals of 5 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 5 in chloroform. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.17 (d, 12 H, ³J_HH = 6.7 Hz, iPr–CH₃), 1.33 (d, 12 H, ³J_HH = 6.7 Hz, iPr–CH₃), 2.67 (sept, 4 H, ³J_HH = 6.1 Hz, iPr–CH), 6.77 (d_br, 2 H, acridine–CH), 7.46 (t, 2 H, ³J_HH = 7.4 Hz, acridine–CH), 7.50 (s, 2 H, N–CH–CH–N), 7.54 (d, 4 H, ³J_HH = 7.9 Hz, IDipp-aryl-C_metaH), 7.57 (t, 2 H, ³J_HH = 7.7 Hz, IDipp-aryl-C_paraH), 7.83 (t, 2 H, ³J_HH = 7.8 Hz, acridine–CH), 8.06 (d, 2 H, ³J_HH = 8.3 Hz, acridine–CH), 9.05 (s, 1 H, acridine–CH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 24.0 (iPr–CH₃), 25.3 (iPr–CH₃), 29.1 (iPr–CH), 124.5 (N–CH–CH–N), 124.9 (IDipp-aryl-C_meta), 127.15 (acridine–C), 127.21 (IDipp-aryl-C_para), 129.6 (acridine–CH), 131.4 (acridine–CH), 134.27 (IDipp-aryl-C_ipso), 134.32 (acridine–CH), 142.3 (acridine–CH), 146.7 (IDipp-aryl-C_ortho), 148.0 (acridine–C), 177.5 (N–C–N); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.2 (dm, 1 F, ¹J_PF = 890 Hz, PF), −80.2 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 904 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 81 Hz, CF₂), −116.3 (dm, 4 F, ²J_PF = 96 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.2 (tdm, ¹J_PF = 905 Hz, ¹J_PF = 891 Hz); IR ([cm⁻¹]): 3173 (vw), 3147 (vw), 3076 (vw), 2963 (m), 2927 (w), 2873 (vw), 1671 (vw), 1620 (w), 1591 (vw), 1577 (w), 1546 (vw), 1521 (w), 1464 (w), 1414 (m), 1399 (w), 1388 (vw), 1365 (vw), 1349 (vw), 1313 (m), 1258 (vw), 1212 (vs), 1182 (s), 1130 (s), 1115 (w), 1099 (s), 1070 (m), 1010 (vw), 998 (vw), 963 (m), 935 (w), 851 (vw), 803 (s), 784 (w), 759 (m), 738 (m), 719 (m), 703 (m), 671 (w), 636 (w), 619 (s), 581 (w), 535 (m), 504 (w), 494 (w), 486 (w), 443 (w), 430 (w), 421 (w), 407 (w); HRMS (ESI) m/z [M]⁺ calcd for C₄₀H₄₅CuN₃: 630.2910, found: 630.2896; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9457; elemental analysis calcd (%) for C₄₆H₄₅CuF₁₈N₃P: C 51.33, H 4.21, N 3.90; found: C 51.09, H 4.21, N 3.92.

[(IDipp)Cu(η¹-O=C₁₃H₉N)]⁺FAP⁻ (6). A solution of IIa (120 mg, 113 μmol) and acridone (22.1 mg, 113 μmol) in dichloro methane (5 mL) was stirred for 4 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 6 (108 mg, 98.9 μmol, 87%) as a green solid. Single crystals of 6 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 6 in chloroform. ¹H NMR (400.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.26 (d, 12 H, ³J_HH = 7.7 Hz, iPr–CH₃), 1.28 (d, 12 H, ³J_HH = 7.7 Hz, iPr–CH₃), 2.62 (sept, 4 H, ³J_HH = 6.2 Hz, iPr–CH), 7.13 (t, 2 H, ³J_HH = 6.5 Hz, acridone–CH), 7.32 (s, 2 H, N–CH–CH–N), 7.38 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.59 (t, 2 H, ³J_HH = 7.6 Hz, IDipp-aryl-C_paraH), 7.67 (d, 2 H, acridone–CH), 7.76 (t, 3 H, acridone–CH), 8.00 (d, 2 H, ³J_HH = 6.2 Hz, acridone–CH), 9.71 (s, 1 H, acridone–NH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 24.0 (iPr–CH₃), 25.0 (iPr–CH₃), 29.0 (iPr–CH), 118.9 (acridone–CH), 123.5 (acridone–CH), 124.3 (N–CH–CH–N), 124.7 (IDipp-aryl-C_meta), 131.3 (IDipp-aryl-C_para), 134.2 (IDipp-aryl-C_ipso), 135.5 (acridone–CH), 140.9 (acridone–C), 145.8 (IDipp-aryl-C_ortho), 177.9 (N–C–N); one out of four signals for the acridone–CH-groups, one out of two signals for the quaternary carbon atoms as well as the signal for the carbonyl carbon atom were not detected; ¹⁹F NMR (376.8 MHz, CDCl₃, 298 K): δ [ppm] = −43.5 (dm, 1 F, ¹J_PF = 889 Hz, PF), −80.1 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −87.9 (dm, 2 F, ¹J_PF = 902 Hz, PF₂), −115.6 (dm, 2 F, ²J_PF = 78 Hz, CF₂), −115.8 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −145.8 (tdm, ¹J_PF = 902 Hz, ¹J_PF = 889 Hz); IR ([cm⁻¹]): 3390 (w), 3179 (vw), 3076 (vw), 2965 (w), 2929 (w), 2872 (vw), 1629 (m), 1593 (w), 1531 (m), 1468 (m), 1414 (w), 1386 (vw), 1365 (vw), 1351 (w), 1311 (m), 1297 (m), 1261 (w), 1216 (vs), 1184 (s), 1162 (s), 1137 (s), 1098 (s), 1087 (s), 1062 (m), 1027 (vw), 968 (m), 937 (w), 862 (vw), 812 (s), 801 (s), 757 (m), 744 (m), 719 (m), 670 (w), 660 (w), 636 (m), 617 (s), 580 (m), 549 (m), 535 (m), 505 (w), 493 (w), 440 (w), 429 (w), 421 (vw); HRMS (ESI) m/z [M]⁺ calcd for C₄₀H₄₅CuN₃O: 646.2859, found: 646.2843; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9451; elemental analysis calcd (%) for C₄₆H₄₅CuF₁₈N₃OP: C 50.58, H 4.15, N 3.85; found: C 50.13, H 4.38, N 3.29.

[(IDipp)Cu(C₄H₁₀S)]⁺FAP⁻ (7). SEt₂ (10.1 μL, 94.4 μmol) was added to a solution of IIa (100 mg, 94.4 μmol) in dichloro methane (8 mL). The reaction mixture was stirred for 4 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 7 (69.0 mg, 69.9 μmol, 74%) as a colorless solid. Single crystals of 7 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 7 in chloroform. ¹H NMR (600.2 MHz, CDCl₃, 298 K): δ [ppm] = 0.83 (t, 6 H, S–CH₂–CH₃, ³J_HH = 7.4 Hz), 1.22 (d, 12 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.27 (12 H, d, ³J_HH = 6.8 Hz, iPr–CH₃), 2.50 (sept, 4 H, ³J_HH = 6.8 Hz, iPr–CH), overlap with 2.46–2.53 (m, 4 H, S–CH₂–CH₃), 7.32 (s, 2 H, N–CH–CH–N), 7.35 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.56 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH); ¹³C{¹H} NMR (150.9 MHz, CDCl₃, 298 K): δ [ppm] = 14.1 (S–CH₂–CH₃), 23.8 (iPr–CH₃), 25.4 (iPr–CH₃), 28.5 (S–CH₂–CH₃), 28.9 (iPr–CH), 124.5 (N–CH–CH–N), 124.7 (IDipp-aryl-C_meta), 131.5 (IDipp-aryl-C_para), 133.7 (IDipp-aryl-C_ipso), 145.8 (IDipp-aryl-C_ortho) 176.3 (N–C–N); ¹⁹F NMR (470.5, CDCl₃, 298 K): δ [ppm] = −45.3 (dm, 1 F, ¹J_PF = 891 Hz, PF), −80.2 (m, 3 F, CF₃), −81.9 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 904 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 82 Hz, CF₂), −116.4 (dm, 4 F, ²J_PF = 97 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.2 (tdm, ¹J_PF = 904 Hz, ¹J_PF = 891 Hz); IR ([cm⁻¹]): 3166 (vw), 3142 (vw), 3075 (vw), 2959 (w), 2929 (w), 2876 (vw), 1665 (vw), 1593 (vw), 1548 (vw), 1462 (m), 1415 (w), 1387 (w), 1366 (w), 1310 (m), 1295 (m), 1257 (w), 1212 (vs), 1179 (s), 1135 (s), 1125 (s), 1097 (s), 1061 (m), 972 (m), 962 (m), 936 (w), 806 (s), 783 (vw), 762 (m), 743 (m), 723 (m), 700 (s), 676 (vw), 637 (m), 618 (s), 580 (m), 534 (w), 505 (vw), 493 (w), 465 (vw), 439 (w), 429 (w), 422(w); HRMS (ESI) m/z [M]⁺ calcd for C₃₁H₄₆CuN₂S: 541.2678, found: 541.26665; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9462; elemental analysis calcd (%) for C₃₇H₄₆CuF₁₈N₂PS: C 45.01, H 4.70, N 2.84, S 3.25; found: C 46.17, H 4.77, H 2.83, S 2.95.

[(IDipp)Cu(C₄H₈S)]⁺FAP⁻ (8). THT (12.5 μL, 142 μmol) was added to a solution of IIa (150 mg, 142 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 4 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (7 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 8 (106 mg, 108 μmol, 76%) as a colorless solid. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.21 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.27 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.72–1.76 (m, 4 H, S–CH₂–CH₂), 2.49 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 2.62–2.66 (m, 4 H, S–CH₂–CH₂) 7.32 (s, 2 H, N–CH–CH–N), 7.36 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.58 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH); ¹³C{¹H} NMR (100.6 MHz, CDCl₃, 298 K): δ [ppm] = 23.7 (iPr–CH₃), 25.4 (iPr–CH₃), 28.9 (iPr–CH), 30.9 (S–CH₂–CH₂), 35.4 (S–CH₂–CH₂), 124.6 (N–CH–CH–N), 124.8 (IDipp-aryl-C_meta), 131.5 (IDipp-aryl-C_para), 133.8 (IDipp-aryl-C_ipso), 145.7 (IDipp-aryl-C_ortho), 176.3 (N–C–N); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.3 (dm, 1 F, ¹J_PF = 891 Hz, PF), −80.2 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 904 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 82 Hz, CF₂), −116.4 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.3 (tdm, ¹J_PF = 904 Hz, ¹J_PF = 890 Hz); IR ([cm⁻¹]): 3167 (vw), 3142 (vw), 3076 (vw), 2967 (w), 2931 (w), 2874 (vw), 1721 (vw), 1593 (vw), 1575 (vw), 1548 (vw), 1468 (w), 1412 (w), 1388 (vw), 1364 (vw), 1295 (m), 1258 (vw), 1212 (vs), 1179 (s), 1144 (s), 1134 (s), 1125 (s), 1097 (s), 1060 (m), 972 (m), 962 (m), 936 (w), 883 (vw), 807 (s), 782 (m), 762 (s), 741 (m), 724 (m), 699 (m), 637 (vw), 618 (vs), 580 (m), 533 (m), 505 (m), 495 (m), 438 (m), 429 (m); HRMS (ESI) m/z [M]⁺ calcd for C₃₁H₄₄CuN₂S: 539.2521, found: 539.2505; m/zFAP⁻ calcd for: 444.9450, found: 444.9438; elemental analysis calcd (%) for C₃₇H₄₄CuF₁₈N₂PS: C 45.10, H 4.50, N 2.84, S 3.25; found: C 46.63, H 4.58, N 2.77, S 2.25.

[(IDipp)Cu(PCy₃)]⁺FAP⁻ (9). A solution of IIa (150 mg, 142 μmol) and PCy₃ (39.7 mg, 142 μmol) in dichloro methane (7 mL) was stirred for 5 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 10 mL) and dried in vacuo to yield 9 (142 mg, 121 μmol, 85%) as a colorless solid. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 0.79–1.66 (m, 33 H, PCy₃), 1.24 (d, 12 H, ³J_HH = 7.3 Hz, iPr–CH₃), 1.26 (d, 12 H, ³J_HH = 7.3 Hz, iPr–CH₃), 2.54 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 7.32 (s, 2 H, N–CH–CH–N), 7.34 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.53 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 24.1 (iPr–CH₃), 24.9 (iPr–CH₃), 25.58 (PCy₃), 25.59 (PCy₃), 26.9 (PCy₃), 27.0 (PCy₃), 29.0 (iPr–CH), 30.85 (PCy₃), 30.86 (PCy₃), 31.2 (PCy₃), 31.3 (PCy₃), 124.3 (N–CH–CH–N), 124.4 (IDipp-aryl-C_meta), 131.1 (IDipp-aryl-C_para), 134.0 (IDipp-aryl-C_ipso), 145.8 (IDipp-aryl-C_ortho), 178.0 (N–C–N); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.3 (dm, 1 F, ¹J_PF = 891 Hz, PF), −80.2 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.5 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 83 Hz, CF₂), −116.4 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.3 (tdm, ¹J_PF = 904 Hz, ¹J_PF = 891 Hz), 27.2 (PCy₃); IR ([cm⁻¹]): 3171 (vw), 3144 (vw), 3078 (vw), 2931 (m), 2854 (m), 1717 (vw), 1592 (vw), 1549 (vw), 1464 (vw), 1448 (m), 1411 (m), 1387 (w), 1364 (w), 1294 (m), 1272 (vw), 1213 (vs), 1175 (s), 1135 (s), 1124 (s), 1098 (s), 1070 (m), 1061 (w), 1004 (vw), 970 (m), 959 (w), 937 (w), 920 (w), 890 (w), 851 (vw), 816 (s), 784 (vw), 762 (m), 742 (m), 725 (m), 700 (w), 636 (w), 618 (vs), 580 (m), 533 (w), 516 (w), 505 (m), 493 (m), 475 (w), 466 (w), 438 (m), 430 (w); HRMS (ESI) m/z [M]⁺ calcd for C₄₅H₆₉CuN₂P: 731.4494, found: 731.4475; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9443; elemental analysis calcd (%) for C₅₁H₆₉CuF₁₈N₂P₂: C 52.02, H 5.91, N 2.38; found: C 52.31, H 5.70, N 2.67.

[{(IDipp)Cu}₂(C₂N₃H₃)₂]²⁺2FAP⁻ (10). A solution of IIa (150 mg, 142 μmol) and 1,2,4-triazole (9.78 mg, 142 μmol) in dichloro methane (7 mL) was stirred for 4 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 10 (109 mg, 56.4 μmol, 40%) as a colorless solid. Single crystals of 10 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 10 in chloroform. ¹H NMR (400.1 MHz, CDCl₃, 298 K): δ [ppm] = 0.94–1.06 (m, 24 H, iPr–CH₃), 1.22 (d, 24 H, ³J_HH = 6.9 Hz, iPr–CH₃), 2.52 (sept, 8 H, ³J_HH = 6.9 Hz, iPr–CH), 5.88 (s_br, 4 H, triazole-CH), 7.23 (s, 4 H, N–CH–CH–N), 7.35 (d, 8 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.65 (t, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH), 10.65 (s_br, 2 H, triazole–NH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 23.8 (iPr–CH₃), 24.6 (iPr–CH₃), 28.8 (iPr–CH), 123.8 (N–CH–CH–N), 125.0 (IDipp-aryl-C_meta), 131.9 (IDipp-aryl-C_para), 135.3 (IDipp-aryl-C_ipso), 146.0 (IDipp-aryl-C_ortho), 182.0 (N–C–N); the signal for the triazol–CH-groups were not detected; ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −43.8 (dm, 1 F, ¹J_PF = 881 Hz, PF), −80.1 (m, 3 F, CF₃), −81.7 (m, 6 F, CF₃), −88.5 (dm, 2 F, ¹J_PF = 902 Hz, PF₂), −115.5 (dm, 2 F, ²J_PF = 80 Hz, CF₂), −115.6 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −145.0 (tdm, ¹J_PF = 899 Hz, ¹J_PF = 881 Hz); IR ([cm⁻¹]): 3386 (vw), 3147 (w), 3075 (vw), 2968 (w), 2933 (w), 2875 (vw), 1723 (vw), 1592 (vw), 1544 (vw), 1504 (vw), 1463 (w), 1419 (w), 1405 (vw), 1390 (vw), 1370 (vw), 1352 (vw), 1296 (m), 1258 (vw), 1212 (vs), 1185 (s), 1137 (s), 1125 (s), 1098 (s), 1061 (m), 964 (m), 937 (w), 863 (vw), 805 (m), 758 (vw), 743 (m), 720 (m), 679 (w), 667 (w), 637 (w), 618 (vs), 581 (w), 551 (vw), 534 (w), 505 (vw), 494 (w), 465 (vw), 438 (w), 430 (w); HRMS (ESI) m/z [M]⁺ calcd for 520.2502, found: 520.2484; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9445; elemental analysis calcd (%) for C₇₀H₇₈Cu₂F₃₆N₁₀P₂: C 43.51, H 4.07, N 7.25; found: C 43.99, H 4.35, N 7.20.

[{(cAAC^Me)Cu}₂{C₆H₁₂N₂}]²⁺2FAP⁻ (11). A suspension of IIb (100 mg, 105 μmol) and DABCO (11.7 mg, 105 μmol) in dichloro methane (5 mL) was stirred for 6 h at room temperature and the suspension was filtered over a plug of Celite. All volatiles of the filtrate were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 11 (55.0 mg, 53.2 μmol, 62%) as a colorless solid. Single crystals of 11 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 11 in dichloro methane. ¹H NMR (500.1 MHz, CD₂Cl₂, 298 K): δ [ppm] = 1.18 (d, 12 H, ³J_HH = 6.7 Hz, iPr–CH₃), 1.33 (d, 12 H, ³J_HH = 6.7 Hz, iPr–CH₃), 1.37 (s, 12 H, Cu–C–C(CH₃)₂), 1.41 (s, 12 H, N–C(CH₃)₂), 2.12 (s, 4 H, CH₂), 2.78 (sept, 4 H, ³J_HH = 6.8 Hz, iPr–CH), 2.86 (s_br, 12 H, DABCO–CH₂), 7.33 (d, 4 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_metaH), 7.48 (t, 2 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CD₂Cl₂, 298 K): δ [ppm] = 22.3 (iPr–CH₃), 27.4 (iPr–CH₃), 28.1 (Cu–C–C(CH₃)₂), 29.41 (N–C(CH₃)₂/iPr–CH), 29.47 (N–C(CH₃)₂/iPr–CH), 47.8 (DABCO–CH₂), 49.4 (CH₂), 54.1 (Cu–C–C(CH₃)₂), 83.7 (N–C(CH₃)₂), 125.7 (cAAC^Me-aryl-C_meta), 131.2 (cAAC^Me-aryl-C_para), 134.7 (cAAC^Me-aryl-C_ipso), 145.1 (cAAC^Me-aryl-C_ortho) 246.1 (N–C–Cu); ¹⁹F NMR (470.5 MHz, CD₂Cl₂, 298 K): δ [ppm] = −45.2 (dm, 1 F, ¹J_PF = 890 Hz, PF), −80.5 (m, 3 F, CF₃), −82.1 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 84 Hz, CF₂), −116.4 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CD₂Cl₂, 298 K): δ [ppm] = −147.3 (tdm, ¹J_PF = 902 Hz, ¹J_PF = 890 Hz); IR ([cm⁻¹]): 2965 (m), 2942 (m), 2875 (w), 1588 (vw), 1530 (m), 1461 (m), 1387 (vw), 1374 (vw), 1364 (vw), 1312 (w), 1293 (w), 1207 (m), 1184 (m), 1136 (m), 1125 (m), 1100 (m), 1069 (m), 1054 (m), 1023 (w), 974 (m), 959 (m), 898 (vw), 814 (m), 779 (w), 759 (w), 720 (m), 637 (w), 618 (m), 580 (w), 532 (w), 496 (m), 467 (w), 439 (w); elemental analysis calcd (%) for C₅₈H₇₄Cu₂F₃₆N₄P₂: C 40.97, H 4.39, N 3.30; found: C 41.38, H 4.36, N 3.61.

[{(cAAC^Me)Cu}₂{C₄H₄N₂}]²⁺2FAP⁻ (12). A suspension IIb (100 mg, 105 μmol) and pyrazine (8.34 mg, 105 μmol) in dichloro methane (5 mL) was stirred for 3 h at room temperature and the suspension was filtered over a plug of Celite. All volatiles of the filtrate were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 12 (59.0 mg, 35.4 μmol, 68%) as an off-white solid. Single crystals of 12 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 12 in dichloro methane. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.16 (d, 12 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.36 (d, 12 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.44 (s, 12 H, N–C(CH₃)₂), 1.47 (s, 12 H, Cu–C–C(CH₃)₂), 2.18 (s, 4 H, CH₂), 2.84 (sept, 4 H, ³J_HH = 6.8 Hz, iPr–CH), 7.37 (d, 4 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_metaH), 7.53 (t, 2 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_paraH), 8.27 (s_br, 4 H, pyrazine-aryl-CH); ¹³C{¹H} NMR (125.8 MHz, CD₂Cl₂, 298 K): δ [ppm] = 22.3 (iPr–CH₃), 27.6 (iPr–CH₃), 28.1 (Cu–C–C(CH₃)₂), 29.45 (N–C(CH₃)₂/iPr–CH), 29.47 (N–C(CH₃)₂/iPr–CH), 49.5 (CH₂), 54.3 (Cu–C–C(CH₃)₂), 83.8 (N–C(CH₃)₂), 125.8 (cAAC^Me-aryl-C_meta), 131.3 (cAAC^Me-aryl-C_para), 134.6 (cAAC^Me-aryl-C_ipso), 145.4 (cAAC^Me-aryl-C_ortho), 147.0 (pyrazine-aryl-CH), 245.5 (N–C–Cu); ¹⁹F NMR (470.5 MHz, CD₂Cl₂, 298 K): δ [ppm] = −45.0 (dm, 1 F, ¹J_PF = 890 Hz, PF), −80.5 (m, 3 F, CF₃), −82.1 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 902 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 88 Hz, CF₂), −116.4 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CD₂Cl₂, 298 K): δ [ppm] = −147.2 (tdm, ¹J_PF = 902 Hz, ¹J_PF = 888 Hz); IR ([cm⁻¹]): 3146 (vw), 3112 (vw), 3079 (vw), 3061 (vw), 2969 (m), 2945 (m), 2875 (m), 1587 (vw), 1534 (m), 1460 (m), 1432 (m), 1388 (w), 1373 (w), 1365 (w), 1295 (m), 1268 (vw), 1205 (s), 1183 (s), 1137 (s), 1124 (m), 1101 (m), 1070 (m), 1053 (w), 1023 (vw), 975 (m), 932 (w), 899 (vw), 833 (vw), 805 (s), 781 (m), 766 (m), 757 (m), 715 (s), 637 (m), 618 (vs), 600 (m), 580 (m), 553 (w), 532 (m), 494 (m), 468 (w), 437 (m), 428 (m); elemental analysis calcd (%) for C₅₆H₆₆Cu₂F₃₆N₄P₂: C 40.32, H 3.99, N 3.36; found: C 39.72, H 3.47, N 4.12.

[(cAAC^Me)Cu(C₇H₁₀N₂)]⁺FAP⁻ (13). A suspension of IIb (100 mg, 105 μmol) and DMAP (11.7 mg, 105 μmol) in dichloro methane (5 mL) was stirred for 4 h at room temperature and the suspension was filtered over a plug of Celite. All volatiles of the filtrate were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 27 (55.0 mg, 60.0 μmol, 57%) as a colorless solid. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.20 (d, 6 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.35 (d, 6 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.43 (s, 6 H, N–C(CH₃)₂), 1.49 (s, 6 H, Cu–C–C(CH₃)₂), 2.15 (s, 2 H, CH₂), 2.84 (sept, 2 H, ³J_HH = 6.8 Hz, iPr–CH), 3.02 (s, 6 H, DMAP–CH₃), 6.43 (d, 2 H, DMAP–C_metaH), 7.31–7.39 (m, 2 H, DMAP–C_orthoH) 7.34 (d, 2 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_metaH), 7.51 (t, 1 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 22.4 (iPr–CH₃), 26.9 (iPr–CH₃), 28.2 (Cu–C–C(CH₃)₂), 29.10 (iPr–CH, N–C(CH₃)₂), 29.15 (iPr–CH, N–C(CH₃)₂), 39.1 (DMAP–CH₃), 49.3 (CH₂), 82.5 (N–C(CH₃)₂), 107.4 (DMAP–C_metaH), 125.2 (cAAC^Me-aryl-C_meta), 130.5 (cAAC^Me-aryl-C_para), 134.3 (cAAC^Me-aryl-C_ipso), 145.0 (cAAC^Me-aryl-C_ortho), 147.9 (DMAP–C_orthoH), 155.5 (DMAP–C_para), 247.7 (N–C–Cu); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.3 (dm, 1 F, ¹J_PF = 889 Hz, PF), −80.2 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.9 (dm, 2 F, ¹J_PF = 904 Hz, PF₂), −115.8 (dm, 2 F, ²J_PF = 84 Hz, CF₂), −116.3 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.0 (tdm, ¹J_PF = 904 Hz, ¹J_PF = 889 Hz); IR ([cm⁻¹]): 3395 (vw), 2969 (m), 2953 (m), 2926 (m), 2875 (m), 2863 (m), 1791 (vw), 1619 (s), 1590 (w), 1549 (m), 1529 (m), 1458 (w), 1447 (w), 1397 (m), 1374 (w), 1346 (vw), 1312 (m), 1295 (m), 1206 (s), 1178 (s), 1136 (s), 1123 (s), 1097 (m), 1070 (m), 1027 (m), 960 (m), 897 (vw), 810 (vs), 782 (m), 761 (m), 722 (s), 637 (m), 617 (s), 580 (m), 556 (w), 529 (m), 505 (w), 494 (m), 467 (w), 438 (m), 428 (m); HRMS (ESI) m/z [M]⁺ calcd for C₂₇H₄₁CuN₃: 470.2597, found: 470.2579; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9441; elemental analysis calcd (%) for C₃₃H₄₁CuF₁₈N₃P: C 43.26, H 4.51, N 4.59; found: C 43.06, H 4.00, N 5.39.

[(cAAC^Me)Cu(C₄H₁₀S)]⁺FAP⁻ (14). SEt₂ (11.2 μL, 105 μmol) was added to a suspension of IIb (100 mg, 105 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 2 h at room temperature and the suspension was filtered over a plug of Celite. All volatiles of the filtrate were removed under reduced pressure and the remaining solid was suspended in n-hexane (10 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 14 (178 mg, 201 μmol, 74%) as a black solid. ¹H NMR (400.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.07–1.18 (m, 6 H, S–CH₂–CH₃), 1.20 (d, 6 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.35 (d, 6 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.43 (s, 6 H, N–C(CH₃)₂), 1.44 (s, 6 H, Cu–C–C(CH₃)₂), 2.15 (s, 2 H, CH₂), 2.63–2.77 (m, 4 H, S–CH₂–CH₃), 2.81 (sept, 2 H, ³J_HH = 6.3 Hz, iPr–CH), 7.33 (d, 2 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_metaH), 7.48 (t, 1 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_paraH); ¹³C{¹H} NMR (100.6 MHz, CDCl₃, 298 K): δ [ppm] = 14.5 (S–CH₂–CH₃), 22.3 (iPr–CH₃), 27.4 (iPr–CH₃), 28.1 (Cu–C–C(CH₃)₂), 28.4 (S–CH₂–CH₃), 29.23 (iPr–CH, N–C(CH₃)₂), 29.25 (iPr–CH, N–C(CH₃)₂), 49.2 (CH₂), 54.2 (Cu–C–C(CH₃)₂), 83.4 (N–C(CH₃)₂), 125.5 (cAAC^Me-aryl-C_meta), 130.9 (cAAC^Me-aryl-C_para), 134.2 (cAAC^Me-aryl-C_ipso), 145.1 (cAAC^Me-aryl-C_ortho) 245.3 (N–C–Cu); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.2 (dm, 1 F, ¹J_PF = 891 Hz, PF), −80.1 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.5 (dm, 2 F, ¹J_PF = 904 Hz, PF₂), −115.8 (dm, 2 F, ²J_PF = 84 Hz, CF₂), −116.3 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.2 (tdm, ¹J_PF = 904 Hz, ¹J_PF = 890 Hz); IR ([cm⁻¹]): 3066 (vw), 2969 (m), 2948 (m), 2873 (m), 1721(vw), 1588 (vw), 1542 (m), 1459 (m), 1388 (w), 1373 (w), 1366 (w), 1344 (vw), 1310 (m), 1296 (m), 1267 (w), 1211 (s), 1178 (vs), 1126 (s), 1090 (s), 1068 (m), 1013 (vw), 972 (m), 963 (m), 933 (vw), 914 (vw), 896 (vw), 885 (vw), 809 (s), 779 (m), 761 (m), 742 (w), 721 (s), 675 (vw), 636 (m), 616 (vs), 580 (m), 552 (vw), 533 (m), 506 (w), 495 (m), 467 (vw), 439 (w), 428 (w); HRMS (ESI) m/z [M]⁺ calcd for C₂₄H₄₁CuNS: 438.2256, found: 438.2240; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9435; elemental analysis calcd (%) for C₃₀H₄₁CuF₁₈NPS: C 40.75, H 4.67, N 1.58, S 3.63; found: C 40.60, H 4.62, N 1.67, S 3.16.

[(cAAC^Me)Cu(N≡CMe)]⁺FAP⁻ (15). The phosphorane (C₂F₅)₃PF₂ (77.0 μL, 327 μmol) was added at room temperature to a solution of Ic (120 mg, 326 μmol) in acetonitrile (5 mL). The reaction mixture was stirred for 2 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (5 mL) and dried in vacuo to yield 15 (188 mg, 225 μmol, 69%) as a colorless solid. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.19 (d, 6 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.34 (d, 6 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.38 (s, 6 H, N–C(CH₃)₂), 1.42 (s, 6 H, Cu–C–C(CH₃)₂), 2.10 (s, 2 H, CH₂), 2.22 (s, 3 H, N≡C–CH₃), 2.75 (sept, 2 H, ³J_HH = 6.8 Hz, iPr–CH), 7.31 (d, 2 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_metaH), 7.48 (t, 1 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_paraH); ¹³C{¹H}-NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 2.1 (N≡C–CH₃), 22.3 (iPr–CH₃), 27.3 (iPr–CH₃), 28.0 (Cu–C–C(CH₃)₂), 29.18 (iPr–CH/N–C(CH₃)₂), 29.20 (iPr–CH/N–C(CH₃)₂), 49.2 (CH₂), 54.2 (Cu–C–C(CH₃)₂), 83.1 (N–C(CH₃)₂), 118.2 (N≡C), 125.2 (cAAC^Me-aryl-C_meta), 130.7 (cAAC^Me-aryl-C_para), 133.7 (cAAC^Me-aryl-C_ipso), 145.0 (cAAC^Me-aryl-C_ortho), 245.5 (N–C–Cu); ¹⁹F-NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.0 (dm, 1 F, ¹J_PF = 892 Hz, PF), −80.1 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.4 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −115.8 (dm, 2 F, ²J_PF = 83 Hz, CF₂), −116.3 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P-NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.3 (tdm, ¹J_PF = 903 Hz, ¹J_PF = 892 Hz); IR (ATR [cm⁻¹]): 2975 (w), 2948 (w), 2873 (vw), 2323 (vw), 2297 (vw), 1588 (vw), 1524 (vw), 1460 (w), 1388 (vw), 1372 (vw), 1364 (vw), 1309 (w), 1296 (w), 1210 (s), 1180 (s), 1135 (s), 1124 (s), 1097 (m), 1068 (m), 962 (m), 932 (vw), 808 (s), 762 (m), 722 (s), 618 (vs), 580 (m), 533 (m), 494 (w), 467 (vw), 438 (vw), 428 (w); HRMS (ESI) m/z [M]⁺ calcd for C₂₂H₃₄CuN₂: 389.2018, found: 389.2002; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9444; elemental analysis calcd (%) for C₂₈H₃₄CuF₁₈N₂P: (gefunden): C 40.27, H 4.10, N 3.35; found: C 40.81, H 4.26, N 3.51.

[(IDipp)Cu(N≡CMe)₂]⁺FAP⁻ (16). The phosphorane (C₂F₅)₃PF₂ (46.5 μL, 197 μmol) was added at room temperature to a solution of Ia (93.0 mg, 197 μmol) in acetonitrile (3 mL). The reaction mixture was stirred for 1.5 h at room temperature. All volatiles were removed under reduced pressure and the product was dried in vacuo to yield 16 (157 mg, 160 μmol, 81%) as a colorless solid. Single crystals of 16 suitable for X-ray diffraction were obtained by vapor diffusion of n-pentane into a solution of 16 in toluene. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.23 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃) overlap with 1.25 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.99 (s, 6 H, N≡C-CH₃), 2.51 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 7.27 (s, 2 H, N–CH–CH–N), 7.36 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.55 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CD₂Cl₂, 298 K): δ [ppm] = 2.3 (N≡C–CH₃), 24.0 (iPr–CH₃), 24.9 (iPr–CH₃), 29.1 (iPr–CH), 117.3 (N≡C), 124.4 (N–CH–CH–N), 124.6 (IDipp-aryl-C_meta), 131.1 (IDipp-aryl-C_para), 134.6 (IDipp-aryl-C_ipso), 146.2 (IDipp-aryl-C_ortho), 178.3 (N–C–N); ¹⁹F NMR (470.5 MHz, CD₂Cl₂, 298 K): δ [ppm] = −45.1 (dm, 1 F, ¹J_PF = 889 Hz, PF), −80.6 (m, 3 F, CF₃), −82.3 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 902 Hz, PF₂), −116.1 (dm, 2 F, ²J_PF = 83 Hz, CF₂), −116.7 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CD₂Cl₂, 298 K): δ [ppm] = −147.7 (tdm, ¹J_PF = 902 Hz, ¹J_PF = 889 Hz); IR ([cm⁻¹]): 3186 (vw), 3151 (vw), 2967 (m), 2931 (w), 2871 (w), 2314 (vw), 1681 (vw), 1580 (vw), 1552 (vw), 1471 (m), 1408 (w), 1385 (w), 1365 (w), 1329 (w), 1310 (m), 1258 (vw), 1213 (vs), 1189 (vs), 1138 (s), 1127 (s), 1088 (s), 1061 (m), 967 (m), 949 (w), 937 (w), 806 (s), 763 (s), 742 (m), 724 (vs), 695 (w), 636 (m), 617 (vs), 602 (m), 580 (m), 560 (vw), 534 (w), 506 (w), 495 (w), 443 (w), 429 (w), 422 (w); HRMS (ESI) m/z [M − CH₃CN]⁺ calcd for. C₂₉H₃₉CuN₃: 492.2440, found: 492.2427; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9458; elemental analysis calcd (%) for C₃₇H₄₂CuF₁₈N₄P: C 45.38, H 4.32, N 5.72; found: C 45.75, H 4.38, N 5.12.

[(IDipp)Cu(N≡CPh)]⁺FAP⁻ (17). The phosphorane (C₂F₅)₃PF₂ (75.0 μL, 319 μmol) was added at room temperature to a solution of Ia (150 mg, 318 μmol) and benzonitrile (32.6 μL, 319 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 3 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 17 (235 mg, 262 μmol, 82%) as a colorless solid. Single crystals of 17 suitable for X-ray diffraction were obtained by vapor diffusion of n-pentane into a saturated solution of 17 in toluene. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.26 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.27 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 2.51 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 7.30 (s, N–CH–CH–N), 7.37 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.54 (t_br, 2 H, ³J_HH = 7.6 Hz, benzonitrile-aryl-C_metaH), 7.58 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH), 7.65 (d_br, 2 H, ³J_HH = 7.6 Hz, benzonitrile-aryl-C_orthoH), 7.77 (t_br, 1 H, ³J_HH = 7.6 Hz, benzonitrile-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 23.8 (iPr–CH₃), 25.2 (iPr–CH₃), 28.9 (iPr–CH), 106.9 (benzonitrile-aryl-C_ipso), 118.3 (N≡C), 124.71 (N–CH–CH–N), 124.74 (IDipp-aryl-C_meta), 130.0 (benzonitrile-aryl-C_meta), 131.4 (IDipp-aryl-C_para), 133.6 (benzonitrile-aryl-C_ortho), 133.7 (IDipp-aryl-C_ipso), 136.3 (benzonitrile-aryl-C_para), 145.7 (IDipp-aryl-C_ortho), 175.5 (N–C–N); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.3 (dm, 1 F, ¹J_PF = 892 Hz, PF), −80.2 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 82 Hz, CF₂), −116.4 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.3 (tdm, ¹J_PF = 903 Hz, ¹J_PF = 892 Hz); IR ([cm⁻¹]): 3186 (vw), 3134 (vw), 2967 (w), 2927 (w), 2874 (w), 2275 (w), 1597 (w), 1547 (vw), 1468 (w), 1414 (w), 1389 (vw), 1367 (vw), 1312 (m), 1215 (vs), 1184 (s), 1138 (s), 1125 (m), 1111 (w), 1089 (m), 1061 (w), 963 (m), 934 (w), 805 (s), 758 (s), 743 (m), 716 (vs), 702 (w), 681 (w), 636 (w), 618 (vs), 601 (w), 581 (w), 551 (w), 534 (w), 505 (w), 494 (vw), 441 (w), 429 (w), 420 (w); HRMS (ESI) m/z [M]⁺ calcd for C₃₄H₄₁CuN₃: 554.2597, found: 554.2583; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9426; elemental analysis calcd (%) for C₄₀H₄₁CuF₁₈N₃P: C 48.03, H 4.13, N 4.20; found: C 48.23, H 4.07, N 4.42.

[(IDipp)Cu(NH₂Ph)]⁺FAP⁻ (18). The phosphorane (C₂F₅)₃PF₂ (75.0 μL, 319 μmol) was added at room temperature to a solution of Ia (150 mg, 318 μmol) and aniline (29.2 μL, 320 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 1.5 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 18 (197 mg, 199 μmol, 62%) as a colorless solid. ¹H NMR (500.1 MHz, CD₂Cl₂, 298 K): δ [ppm] = 1.11 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.22 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 2.45 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 4.74 (s, 2 H, NH₂), 6.51 (m, 2 H, aniline-aryl-C_orthoH), 7.16 (m, 3 H, overlap of aniline-aryl-C_metaH and aniline-aryl-C_paraH), 7.28 (s, 2 H, N–CH–CH–N), 7.33 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.57 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CD₂Cl₂, 298 K): δ [ppm] = 23.9 (iPr–CH₃), 25.0 (iPr–CH₃), 29.1 (iPr–CH), 120.5 (aniline-aryl-C_ortho), 124.7 (N–CH–CH–N), 124.9 (IDipp-aryl-C_meta), 126.5 (aniline-aryl-C_para), 130.6 (aniline-aryl-C_meta), 131.4 (IDipp-aryl-C_para), 134.3 (IDipp-aryl-C_ipso), 136.3 (aniline-aryl-C_ipso), 146.0 (IDipp-aryl-C_ortho), 176.9 (N–C–N); ¹⁹F NMR (470.5 MHz, CD₂Cl₂, 298 K): δ [ppm] = −45.0 (dm, 1 F, ¹J_PF = 889 Hz, PF), −80.6 (m, 3 F, CF₃), −82.2 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 904 Hz, PF₂), −116.0 (dm, 2 F, ²J_PF = 84 Hz, CF₂), −116.5 (dm, 4 F, ²J_PF = 99 Hz, CF₂); ³¹P NMR (202.4 MHz, CD₂Cl₂, 298 K): δ [ppm] = −147.1 (tdm, ¹J_PF = 904 Hz, ¹J_PF = 889 Hz); IR ([cm⁻¹]): 3325 (w), 3264 (w), 2967 (w), 2874 (w), 1597 (w), 1577 (w), 1550 (vw), 1494 (w), 1462 (w), 1414 (w), 1387 (vw), 1367 (vw), 1295 (m), 1211 (vs), 1186 (s), 1137 (m), 1125 (s), 1098 (m), 971 (m), 937 (vw), 807 (s), 759 (s), 722 (s), 693 (m), 637 (w), 617 (vs), 580 (w), 532 (m), 495 (w), 467 (vw), 438 (w), 429 (w); HRMS (ESI) m/z [M]⁺ calcd for C₃₃H₄₃CuN₃: 544.2753, found: 544.2734; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9431; elemental analysis calcd (%) for C₃₉H₄₃CuF₁₈N₃P: C 47.30, H 4.38, N 4.24; found: C 46.99, H 4.31, N 4.39.

[(SIDipp)Cu(NH₂Ph)]⁺FAP⁻ (19). The phosphorane (C₂F₅)₃PF₂ (27.1 μL, 297 μmol) was added at room temperature to a solution of Ib (140 mg, 296 μmol) and aniline (70.0 μL, 297 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 2 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 19 (222 mg, 224 μmol, 76%) as a colorless solid. Single crystals of 19 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 19 in toluene. ¹H NMR (500.1 MHz, CD₂Cl₂, 298 K): δ [ppm] = 1.16 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.33 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 2.98 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 4.10 (s, 4 H, N–CH₂–CH₂–N), 4.24 (br, 2 H, NH₂), 6.35 (m, 2 H, aniline-aryl-C_orthoH), 7.08 (m, 3 H, overlap of aniline-aryl-C_metaH and aniline-aryl-C_paraH), 7.27 (d, 4 H, ³J_HH = 7.8 Hz, SIDipp-aryl-C_metaH), 7.48 (t, 2 H, ³J_HH = 7.8 Hz, SIDipp-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CD₂Cl₂, 298 K): δ [ppm] = 23.9 (iPr–CH₃), 25.7 (iPr–CH₃), 29.2 (iPr–CH), 54.4 (N–CH₂–CH₂–N), 119.9 (aniline-aryl-C_ortho), 125.2 (SIDipp-aryl-C_meta), 125.7 (aniline-aryl-C_para), 130.5 (aniline-aryl-C_meta), 130.7 (SIDipp-aryl-C_para), 134.1 (SIDipp-aryl-C_ipso), 137.5 (aniline-aryl-C_ipso), 147.1 (SIDipp-aryl-C_ortho), 200.4 (N–C–N); ¹⁹F NMR (470.5 MHz, CD₂Cl₂, 298 K): δ [ppm] = −45.1 (dm, 1 F, ¹J_PF = 891 Hz, PF), −80.6 (m, 3 F, CF₃), −82.3 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 902 Hz, PF₂), −116.1 (dm, 2 F, ²J_PF = 83 Hz, CF₂), −116.6 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CD₂Cl₂, 298 K): δ [ppm] = −147.4 (tdm, ¹J_PF = 902 Hz, ¹J_PF = 891 Hz); IR ([cm⁻¹]): 3324 (vw), 3267 (w), 2964 (w), 2926 (w), 2875 (w), 1601 (w), 1579 (w), 1493 (m), 1464 (m), 1388 (vw), 1367 (vw), 1310 (m), 1296 (m), 1276 (m), 1212 (vs), 1179 (s), 1137 (m), 1126 (m), 1100 (m), 1057 (w), 1016 (vw), 972 (w), 935 (vw), 806 (m), 760 (m), 724 (m), 692 (w), 637 (w), 618 (vs), 581 (w), 548 (vw), 532 (w), 505 (vw), 495 (vw), 439 (w); HRMS (ESI) m/z [M]⁺ calcd for C₃₃H₄₅CuN₃: 546.2910, found: 546.2893; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9429; elemental analysis calcd (%) for C₃₉H₄₅CuF₁₈N₃P: C 47.21, H 4.57, N 4.23; found: C 47.36, H 4.72, N 4.34.

[(cAAC^Me)Cu(NH₂Ph)]⁺FAP⁻ (20). The phosphorane (C₂F₅)₃PF₂ (24.8 μL, 272 μmol) was added at room temperature to a solution of Ic (100 mg, 272 μmol) and aniline (64.0 μL, 272 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 2 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 20 (110 mg, 124 μmol, 46%) as a colorless solid. Single crystals of 20 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 20 in toluene. ¹H NMR (500.1 MHz, CD₂Cl₂, 298 K): δ [ppm] = 0.99 (d, 6 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.29 (d, 6 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.39 (s, 6 H, N–C(CH₃)₂), 1.41 (s, 6 H, Cu–C–C(CH₃)₂), 2.11 (s, 2 H, CH₂), 2.75 (sept, 2 H, ³J_HH = 6.8 Hz, iPr–CH), 4.58 (br, 2 H, NH₂), 6.56 (br, 2 H, aniline-aryl-C_orthoH), 7.16 (m, 3 H, overlap of aniline-aryl-C_metaH and aniline-aryl-C_paraH), 7.26 (d, 2 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_metaH), 7.48 (t, 1 H, ³J_HH = 7.8 Hz, cACC^Me-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CD₂Cl₂, 298 K): δ [ppm] = 22.5 (iPr–CH₃), 27.1 (iPr–CH₃), 28.1 (Cu–C–C(CH₃)₂), 29.35 (iPr–CH), 29.41 (N–C(CH₃)₂), 49.6 (CH₂), 54.3 (Cu–C–C(CH₃)₂), 83.3 (N–C(CH₃)₂), 120.9 (aniline-aryl-C_ortho), 125.7 (cAAC^Me-aryl-C_meta), 126.5 (aniline-aryl-C_para), 130.4 (aniline-aryl-C_meta), 130.7 (cAAC^Me-aryl-C_para), 134.9 (cAAC^Me-aryl-C_ipso), 137.2 (aniline-aryl-C_ipso), 145.2 (cAAC^Me-aryl-C_ortho), 246.7 (N–C–Cu); ¹⁹F NMR (470.5 MHz, CD₂Cl₂, 298 K): δ [ppm] = −44.8 (dm, 1 F, ¹J_PF = 889 Hz, PF), −80.5 (m, 3 F, CF₃), −82.1 (m, 6 F, CF₃), −88.5 (dm, 2 F, ¹J_PF = 901 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 84 Hz, CF₂), −116.3 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CD₂Cl₂, 298 K): δ [ppm] = −147.1 (tdm, ¹J_PF = 901 Hz, ¹J_PF = 889 Hz); IR ([cm⁻¹]): 3347 (w), 3296 (w), 2963 (w), 2874 (vw), 1605 (w), 1580 (w), 1535 (vw), 1497 (w), 1463 (w), 1391 (vw), 1373 (vw), 1366 (vw), 1311 (m), 1298 (m), 1214 (vs), 1182 (vs), 1123 (s), 1099 (s), 1085 (w), 1017 (vw), 967 (m), 933 (w), 897 (w), 810 (s), 780 (w), 750 (m), 714 (s), 690 (m), 636 (w), 617 (vs), 580 (m), 532 (m), 505 (w), 494 (w), 466 (vw), 439 (vw), 428 (w), 422 (w); HRMS (ESI) m/z [M]⁺ calcd for C₂₆H₃₈CuN₂: 441.2331, found: 441.2316; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9425; elemental analysis calcd (%) for C₃₂H₃₈CuF₁₈N₂P: C 43.32, H 4.32, N 3.16; found: C 43.22, H 4.43, N 3.20.

[(IDipp)Cu(NHPh₂)]⁺FAP⁻ (21). The phosphorane (C₂F₅)₃PF₂ (75.0 μL, 319 μmol) was added at room temperature to a solution of Ia (150 mg, 318 μmol) and diphenylamine (53.8 mg, 318 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 2 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 21 (289 mg, 271 μmol, 85%) as a colorless solid. Single crystals of 21 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 21 in chloroform. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.02 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.20 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 2.42 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 6.36 (br, 1 H, NH), 6.74 (br, 4 H, diphenylamine-aryl-C_orthoH), 7.10 (t, 2 H, ³J_HH = 7.6 Hz, diphenylamine-aryl-C_paraH), 7.18 (t, 4 H, ³J_HH = 7.6 Hz, diphenylamine-aryl-C_metaH), 7.27 (s, 2 H, N–CH–CH–N), 7.33 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.60 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 24.0 (iPr–CH₃), 24.7 (iPr–CH₃), 28.9 (iPr–CH), 121.1 (diphenylamine-aryl-C_ortho), 124.4 (N–CH–CH–N), 124.6 (IDipp-aryl-C_meta), 125.4 (diphenylamine-aryl-C_para), 130.0 (diphenylamine-aryl-C_meta), 131.3 (IDipp-aryl-C_para), 134.0 (IDipp-aryl-C_ipso), 141.8 (diphenylamine-aryl-C_ipso), 145.7 (IDipp-aryl-C_ortho), 176.8 (N–C–N); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −44.9 (dm, 1 F, ¹J_PF = 891 Hz, PF), −80.2 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.5 (dm, 2 F, ¹J_PF = 904 Hz, PF₂), −115.7 (dm, 2 F, ²J_PF = 82 Hz, CF₂), −116.1 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −146.8 (tdm, ¹J_PF = 904 Hz, ¹J_PF = 891 Hz); IR ([cm⁻¹]): 3270 (vw), 3202 (vw), 3141 (vw), 2964 (w), 2927 (vw), 2874 (w), 1592 (w), 1510 (w), 1491 (w), 1469 (w), 1414 (w), 1387 (vw), 1366 (vw), 1310 (m), 1295 (m), 1212 (vs), 1182 (s), 1136 (m), 1124 (m), 1095 (m), 1069 (vw), 1060 (vw), 1026 (vw), 1005 (vw), 973 (m), 936 (w), 805 (m), 751 (m), 724 (m), 690 (m), 637 (w), 618 (vs), 580 (w), 533 (w), 495 (w), 483 (vw), 466 (vw), 438 (w), 429 (w); HRMS (ESI) m/z [M]⁺ calcd for C₃₉H₄₇CuN₃: 620.3066, found: 620.3049; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9433; elemental analysis calcd (%) for C₄₅H₄₇CuF₁₈N₃P: C 50.68, H 4.44, N 3.94; found: C 51.61, H 4.49, N 4.26.

[(IDipp)Cu(NC₅H₅)]⁺FAP⁻ (22). The phosphorane (C₂F₅)₃PF₂ (75.0 μL, 319 μmol) was added at room temperature to a solution of Ia (150 mg, 318 μmol) and pyridine (26.0 μL, 322 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 2 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (5 mL) and dried in vacuo to yield 22 (215 mg, 216 μmol, 68%) as a colorless solid. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.22 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.28 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 2.56 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 7.32 (s, 2 H, N–CH–CH–N), 7.37 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.59 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH), 7.50 (br, 2 H, pyridine-aryl-C_ortho/metaH), 7.77 (br, 2 H, pyridine-aryl-C_ortho/metaH), 8.02 (br, 1 H, pyridine-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 23.8 (iPr–CH₃), 25.2 (iPr–CH₃), 28.9 (iPr–CH), 124.4 (N–CH–CH–N), 124.7 (IDipp-aryl-C_meta), 126.8 (pyridine-aryl-C_ortho/meta), 131.3 (IDipp-aryl-C_para), 134.1 (IDipp-aryl-C_ipso), 142.1 (pyridine-aryl-C_para), 145.8 (IDipp-aryl-C_ortho), 147.5 (pyridine-aryl-C_ortho/meta), 177.6 (N–C–N); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.1 (dm, 1 F, ¹J_PF = 890 Hz, PF), −80.2 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 905 Hz, PF₂), −115.8 (dm, 2 F, ²J_PF = 84 Hz, CF₂), −116.3 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −146.9 (tdm, ¹J_PF = 905 Hz, ¹J_PF = 890 Hz); IR ([cm⁻¹]): 2963 (w), 2928 (w), 2874 (w), 1640 (vw), 1611 (w), 1600 (w), 1544 (w), 1491 (w), 1469 (w), 1450 (w), 1414 (w), 1388 (vw), 1366 (vw), 1294 (m), 1209 (vs), 1182 (vs), 1136 (s), 1124 (s), 1098 (s), 1070 (m), 972 (m), 961 (m), 936 (vw), 810 (s), 758 (m), 741 (vw), 720 (s), 699 (m), 674 (w), 637 (w), 617 (vs), 581 (m), 532 (w), 495 (w), 467 (vw), 438 (w), 428 (w); HRMS (ESI) m/z [M]⁺ calcd for C₃₂H₄₁CuN₃: 530.2597, found: 530.2577; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9424; elemental analysis calcd (%) for C₃₈H₄₁CuF₁₈N₃P: C 46.75, H 4.23, N 4.30; found: C 45.03, H 3.38, N 4.57.

[(cAAC^Me)Cu(NC₅H₅)]⁺FAP⁻ (23). The phosphorane (C₂F₅)₃PF₂ (84.6 μL, 359 μmol) was added at room temperature to a solution of Ic (132 mg, 359 μmol) and pyridine (29.0 μL, 359 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 2 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 23 (233 mg, 267 μmol, 74%) as a colourless solid. Single crystals of 23 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 23 in 1,2-difluorbenzene. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.20 (d, 12 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.36 (d, 12 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.45 (s, 6 H, N–C(CH₃)₂), 1.50 (s, 6 H, Cu–C–C(CH₃)₂), 2.17 (s, 2 H, CH₂), 2.86 (sept, 2 H, ³J_HH = 6.8 Hz, iPr–CH), 7.36 (d, 2 H, ³J_HH = 7.6 Hz, cAAC^Me-aryl-C_metaH), 7.50 (br, 2 H, pyridine-aryl-C_ortho/metaH), 7.53 (t, 1 H, ³J_HH = 7.6 Hz, cAAC^Me-aryl-C_paraH), 7.97 (br, 3 H, overlap of pyridine-aryl-C_paraH and pyridine-aryl-C_ortho/metaH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ = 22.4 (iPr–CH₃), 27.2 (iPr–CH₃), 28.2 (Cu–C–C(CH₃)₂), 29.26 (iPr–CH), 29.30 (N–C(CH₃)₂), 49.4 (CH₂), 54.1 (Cu–C–C(CH₃)₂), 83.1 (N–C(CH₃)₂), 125.5 (cAAC^Me-aryl-C_meta), 126.7 (pyridine-aryl-C_ortho/meta), 130.8 (cAAC^Me-aryl-C_para), 134.5 (cAAC^Me-aryl-C_ipso), 141.4 (pyridine-aryl-C_para), 145.2 (cAAC^Me-aryl-C_ortho), 149.3 (pyridine-aryl-C_ortho/meta), 247.1 (N–C–Cu); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.1 (dm, 1 F, ¹J_PF = 891 Hz, PF), −80.1 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.5 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −115.8 (dm, 2 F, ²J_PF = 83 Hz, CF₂), −116.3 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.4 (tdm, ¹J_PF = 903 Hz, ¹J_PF = 891 Hz); IR ([cm⁻¹]): 2969 (w), 2937 (w), 2875 (w), 1610 (w), 1585 (vw), 1524 (w), 1491 (vw), 1451 (m), 1389 (vw), 1373 (vw), 1311 (m), 1262 (vw), 1201 (vs), 1178 (vs), 1133 (vs), 1098 (s), 1071 (m), 1052 (vw), 1018 (vw), 964 (s), 930 (w), 897 (vw), 883 (vw), 806 (vs), 781 (m), 755 (m), 717 (vs), 698 (s), 636 (w), 617 (vs), 579 (m), 533 (m), 504 (w), 473 (vw), 443 (vw), 421 (m); HRMS (ESI) m/z [M]⁺ calcd for C₂₅H₃₆CuN₂: 427.2175, found: 427.2161; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9427; elemental analysis calcd (%) for C₃₁H₃₆CuF₁₈N₂P: C 42.64, H 4.16, N 3.21; found: C 43.04, H 4.16, N 3.40.

[(IDipp)Cu(NC₅H₃F₂)]⁺FAP⁻ (24). The phosphorane (C₂F₅)₃PF₂ (74.0 μL, 314 μmol) was added at room temperature to a solution of Ia (148 mg, 314 μmol) and 2,6-difluoropyridine (28.6 μL, 315 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 2 h at room temperature and the suspension was filtered over a plug of Celite. All volatiles of the filtrate were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (3 × 5 mL) and dried in vacuo to yield 24 (255 mg, 252 μmol, 80%) as a colorless solid. Single crystals of 24 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 24 in chloroform. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.22 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.27 (d, 12 H, ³J_HH = 6.9 Hz, iPr–CH₃), 2.54 (sept, 4 H, ³J_HH = 6.9 Hz, iPr–CH), 7.03 (d, 2 H, ³J_HH = 8.2 Hz, pyridine-aryl-C_metaH), 7.32 (s, 2 H, N–CH–CH–N), 7.34 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.55 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH), 8.20 (tt, 1 H, ³J_HH = 8.2 Hz, ⁴J_FH = 7.5 Hz, pyridine-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 24.0 (iPr–CH₃), 24.9 (iPr–CH₃), 29.0 (iPr–CH), 108.3 (m, pyridine-aryl-C_meta), 124.56 (N–CH–CH–N/IDipp-aryl-C_meta), 124.60 (N–CH–CH–N/IDipp-aryl-C_meta), 131.4 (IDipp-aryl-C_para), 133.8 (IDipp-aryl-C_ipso), 145.7 (IDipp-aryl-C_ortho), 150.9 (t, ³J_FC = 9.3 Hz, pyridine-aryl-C_para), 160.5 (dd, ¹J_FC = 262 Hz, ³J_FC = 7.1 Hz, pyridine-aryl-C_ortho), 176.3 (N–C–N); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.3 (dm, 1 F, ¹J_PF = 890 Hz, PF), −64.5 (d, 2 F, ⁴J_FH = 7.5 Hz, pyridine-aryl-C_orthoF), −80.3 (m, 3 F, CF₃), −81.9 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 83 Hz, CF₂), −116.5 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.3 (tdm, ¹J_PF = 903 Hz, ¹J_PF = 890 Hz); IR ([cm⁻¹]): 3178 (vw), 2962 (w), 2929 (w), 2875 (w), 1637 (m), 1621 (vw), 1591 (vw), 1571 (vw), 1548 (vw), 1473 (m), 1415 (w), 1388 (vw), 1367 (vw), 1326 (vw), 1319 (w), 1295 (w), 1272 (w), 1258 (w), 1213 (s), 1180 (s), 1137 (m), 1124 (m), 1098 (m), 1060 (w), 1010 (m), 974 (m), 960 (m), 936 (w), 852 (vw), 809 (m), 800 (m), 761 (m), 722 (s), 703 (vw), 637 (w), 618 (vs), 580 (w), 533 (w), 496 (w), 438 (w), 429 (w); HRMS (ESI) m/z [M]⁺ calcd for C₃₂H₃₉CuF₂N₃: 566.2408, found: 566.2390; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9434; elemental analysis calcd (%) for C₃₈H₃₉CuF₂₀N₃P: C 45.09, H 3.88, N 4.15; found: C 45.49, H 3.85, N 4.20.

[(IDipp)Cu(NC₅H₂F₃)]⁺FAP⁻ (25). The phosphorane (C₂F₅)₃PF₂ (75.0 μL, 319 μmol) was added at room temperature to a solution of Ia (150 mg, 318 μmol) and 2,4,6-trifluoropyridine (30.8 μL, 320 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 3 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 25 (232 mg, 225 μmol, 71%) as a colorless solid. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.21 (d, 12 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.26 (d, 12 H, ³J_HH = 6.8 Hz, iPr–CH₃), 2.52 (sept, 4 H, ³J_HH = 6.8 Hz, iPr–CH), 6.75 (d, 2 H, ³J_FH = 6.8 Hz, pyridine-aryl-C_metaH), 7.32 (s, 2 H, N–CH–CH–N), 7.33 (d, 4 H, ³J_HH = 7.9 Hz, IDipp-aryl-C_metaH), 7.55 (t, 2 H, ³J_HH = 7.9 Hz, IDipp-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 24.0 (iPr–CH₃), 24.9 (iPr–CH₃), 29.0 (iPr–CH), 98.1 (m, pyridine-aryl-C_meta), 124.5 (N–CH–CH–N/IDipp-aryl-C_meta), 124.6 (N–CH–CH–N/IDipp-aryl-C_meta), 131.4 (IDipp-aryl-C_para), 133.7 (IDipp-aryl-C_ipso), 145.6 (IDipp-aryl-C_ortho), 162.0 (pyridine-aryl-C_ortho), 175.9 (pyridine-aryl-C_para), 176.2 (N–C–N); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.4 (dm, 1 F, ¹J_PF = 891 Hz, PF), −61.0 (d, 2 F, ⁴J_FF = 22.6 Hz, pyridine-aryl-C_orthoF), −76.0 (tt, 1 F, ⁴J_FF = 22.6 Hz, ³J_FH = 6.8 Hz, pyridine-aryl-C_paraF), −80.3 (m, 3 F, CF₃), −82.0 (m, 6 F, CF₃), −88.7 (dm, 2 F, ¹J_PF = 904 Hz, PF₂), −116.1 (dm, 2 F, ²J_PF = 83 Hz, CF₂), −116.6 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.5 (tdm, ¹J_PF = 904 Hz, ¹J_PF = 891 Hz); IR ([cm⁻¹]): 3085 (vw), 2965 (w), 2930 (w), 2874 (w), 1674 (vw), 1650 (m), 1593 (m), 1552 (vw), 1523 (vw), 1462 (m), 1413 (w), 1388 (vw), 1367 (vw), 1294 (w), 1213 (vs), 1179 (vs), 1148 (s), 1138 (m), 1125 (s), 1101 (m), 1071 (w), 1060 (w), 1043 (w), 1005 (w), 973 (m), 959 (m), 936 (vw), 854 (w), 815 (m), 807 (m), 761 (m), 726 (s), 702 (vw), 638 (w), 618 (vs), 580 (w), 560 (vw), 533 (w), 517 (w), 495 (w), 465 (vw), 438 (w), 429 (w); HRMS (ESI) m/z [M]⁺ calcd for C₃₂H₃₈CuF₃N₃: 584.2314, found: 584.2299; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9423; elemental analysis calcd (%) for C₃₈H₃₈CuF₂₁N₃P: C 44.30, H 3.72, N 4.08; found: C 44.81, H 3.80, H 4.15.

[{(IDipp)Cu(μ-ONC₅H₅)}₂]²⁺2FAP⁻ (26). The phosphorane (C₂F₅)₃PF₂ (71.6 μL, 304 μmol) was added at room temperature to a solution of Ia (150 mg, 318 μmol) and pyridine-N-oxide (29.0 mg, 305 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 2 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 26 (243 mg, 122 μmol, 81%) as a colorless solid. Single crystals of 26 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 26 in 1,2-difluorobenzene. ¹H NMR (400.1 MHz, CDCl₃, 236.5 K): δ [ppm] = 1.18 (d, 24 H, ³J_HH = 6.9 Hz, iPr–CH₃), 1.25 (d, 24 H, ³J_HH = 6.9 Hz, iPr–CH₃), 2.46 (sept, 8 H, ³J_HH = 6.9 Hz, iPr–CH), 7.32 (s, 4 H, N–CH–CH–N), overlap with 7.37 (d, 8 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.38 (br, 4 H, pyridine-aryl-C_metaH), 7.47 (br, 4 H, pyridine-aryl-C_orthoH), 7.62 (t, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH), 7.71 (t, 2 H, ³J_HH = 7.2 Hz, pyridine-aryl-C_paraH); ¹³C{¹H} NMR (100.6 MHz, CDCl₃, 236.5 K): δ [ppm] = 23.5 (iPr–CH₃), 25.4 (iPr–CH₃), 28.7 (iPr–CH), 124.0 (N–CH–CH–N), 124.6 (IDipp-aryl-C_meta), 127.7(pyridine-aryl-C_meta), 131.1 (IDipp-aryl-C_para), 133.9 (IDipp-aryl-C_ipso), 134.3 (pyridine-aryl-C_para), 138.3 (pyridine-aryl-C_ortho), 145.8 (IDipp-aryl-C_ortho), 176.3 (N–C–N); ¹⁹F NMR (470.5 MHz, CD₂Cl₂, 298 K): δ [ppm] = −45.1 (dm, 1 F, ¹J_PF = 890 Hz, PF), −80.6 (m, 3 F, CF₃), −82.3 (m, 6 F, CF₃), −88.5 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −116.1 (dm, 2 F, ²J_PF = 83 Hz, CF₂), −116.9 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CD₂Cl₂, 298 K): δ [ppm] = −147.5 (tdm, ¹J_PF = 903 Hz, ¹J_PF = 890 Hz); IR ([cm⁻¹]): 3191 (vw), 3124 (vw), 2962 (w), 2926 (w), 2872 (w), 1593 (vw), 1556 (vw), 1469 (m), 1413 (w), 1387 (w), 1365 (w), 1293 (m), 1258 (vw), 1207 (vs), 1181 (vs), 1135 (s), 1124 (s), 1100 (s), 1070 (m), 1027 (w), 975 (m), 961 (m), 937 (w), 835 (w), 814 (s), 806 (s), 761 (s), 744 (m), 715 (s), 668 (m), 637 (w), 617 (vs), 581 (m), 549 (vw), 532 (m), 496 (w), 467 (vw), 452 (vw), 438 (w), 429 (w); HRMS (ESI) m/z [M]_nⁿ⁺ calcd for [C₃₂H₄₁CuN₃O]_n: 546.2546, found: 546.2533; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9429; elemental analysis calcd (%) for C₇₆H₈₂Cu₂F₃₆N₆O₂P₂: C 46.00, H 4.17, N 4.23; found: C 46.14, H 4.13, N 4.52.

[(IDipp)Cu(η¹-O=CPh₂)]⁺FAP⁻ (27). The phosphorane (C₂F₅)₃PF₂ (75.0 μL, 319 μmol) was added at room temperature to a solution of Ia (150 mg, 318 μmol) and benzophenone (58.0 mg, 318 μmol) in dichloro methane (5 mL). The reaction mixture was stirred for 2 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (2 × 5 mL) and dried in vacuo to yield 27 (272 mg, 252 μmol, 79%) as an off-white solid. Single crystals of 27 suitable for X-ray diffraction were obtained by diffusion of n-hexane into a solution of 27 in 1,2-difluorobenzene. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.13 (d, 12 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.24 (d, 12 H, ³J_HH = 6.8 Hz, iPr–CH₃), 2.50 (sept, 4 H, ³J_HH = 6.8 Hz, iPr–CH), 7.28 (s, 2 H, N–CH–CH–N), 7.34 (d, 4 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_metaH), 7.39 (m, 4 H, benzophenone-aryl-C_metaH), 7.52 (dd, 4 H, ³J_HH = 8.4 Hz, ⁴J_HH = 1.2 Hz, benzophenone-aryl-C_orthoH), 7.59 (t, 2 H, ³J_HH = 7.8 Hz, IDipp-aryl-C_paraH), 7.70 (tt, 2 H, ³J_HH = 7.5 Hz, ⁴J_HH = 1.2 Hz, benzophenone-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 23.8 (iPr–CH₃), 25.0 (iPr–CH₃), 28.9 (iPr–CH), 124.7 (N–CH–CH–N/IDipp-aryl-C_meta), 124.8 (N–CH–CH–N/IDipp-aryl-C_meta), 129.4 (benzophenone-aryl-C_meta), 131.1 (benzophenone-aryl-C_ortho), 131.3 (IDipp-aryl-C_para), 134.0 (IDipp-aryl-C_ipso), 135.6 (benzophenone-aryl-C_ipso), 136.0 (benzophenone-aryl-C_para), 145.7 (IDipp-aryl-C_ortho), 175.7 (N–C–N), 206.3 (O=C); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.3 (dm, 1 F, ¹J_PF = 891 Hz, PF), −80.2 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.7 (dm, 2 F, ¹J_PF = 903 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 83 Hz, CF₂), −116.4 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.2 (tdm, ¹J_PF = 903 Hz, ¹J_PF = 891 Hz); IR ([cm⁻¹]): 3137 (vw), 2964 (w), 2927 (w), 2872 (w), 1591 (w), 1558 (m), 1493 (vw), 1461 (w), 1451 (w), 1416 (w), 1388 (vw), 1366 (vw), 1333 (m), 1293 (m), 1212 (vs), 1177 (vs), 1142 (s), 1126 (s), 1098 (s), 1061 (m), 1026 (vw), 999 (vw), 972 (m), 958 (m), 926 (w), 850 (vw), 817 (s), 810 (s), 761 (s), 746 (m), 721 (s), 706 (s), 681 (w), 651 (w), 637 (w), 617 (vs), 580 (m), 532 (w), 496 (w), 438 (w), 429 (w), 411 (vw); HRMS (ESI) m/z [M]⁺ calcd for C₄₀H₄₆CuN₂O: 633.2906, found: 633.2888; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9430; elemental analysis calcd (%) for C₄₆H₄₆CuF₁₈N₂OP: C 51.19, H 4.30, N 2.60; found: C 51.79, H 4.30, N 2.88.

[(cAAC^Me)Cu(THF)]⁺FAP⁻ (28). The phosphorane (C₂F₅)₃PF₂ (77.0 μL, 327 μmol) was added at room temperature to a solution of Ic (120 mg, 326 μmol) in Et₂O (3 mL) and THF (3 mL). The reaction mixture was stirred for 2 h at room temperature. All volatiles were removed under reduced pressure and the remaining solid was suspended in n-hexane (5 mL) and the product was filtered off. The product was washed with n-hexane (5 mL) and dried in vacuo to yield 28 (192 mg, 222 μmol, 68%) as an off-white solid. ¹H NMR (500.1 MHz, CDCl₃, 298 K): δ [ppm] = 1.21 (d, 6 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.35 (d, 6 H, ³J_HH = 6.8 Hz, iPr–CH₃), 1.42 (s, 6 H, N–C(CH₃)₂), 1.43 (s, 6 H, Cu–C–C(CH₃)₂), 1.90 (m, 4 H, THF–C_3,4H₂), 2.14 (s, 2 H, CH₂), 2.80 (sept, 2 H, ³J_HH = 6.8 Hz, iPr–CH), 3.72 (m, 4 H, THF-C_2,5H₂), 7.34 (d, 2 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_metaH), 7.50 (t, 1 H, ³J_HH = 7.8 Hz, cAAC^Me-aryl-C_paraH); ¹³C{¹H} NMR (125.8 MHz, CDCl₃, 298 K): δ [ppm] = 22.4 (iPr–CH₃), 24.8 (THF-C_3,4), 27.0 (iPr–CH₃), 28.1 (Cu–C–C(CH₃)₂), 29.20 (iPr–CH), 29.24 (N–C(CH₃)₂), 49.3 (CH₂), 53.9 (Cu–C–C(CH₃)₂), 73.5 (THF-C_2,5), 83.1 (N–C(CH₃)₂), 125.4 (cAAC^Me-aryl-C_meta), 130.9 (cAAC^Me-aryl-C_para), 134.5 (cAAC^Me-aryl-C_ipso), 145.1 (cAAC^Me-aryl-C_ortho), 245.6 (N–C–Cu); ¹⁹F NMR (470.5 MHz, CDCl₃, 298 K): δ [ppm] = −45.3 (dm, 1 F, ¹J_PF = 891 Hz, PF), −80.1 (m, 3 F, CF₃), −81.8 (m, 6 F, CF₃), −88.6 (dm, 2 F, ¹J_PF = 904 Hz, PF₂), −115.9 (dm, 2 F, ²J_PF = 83 Hz, CF₂), −116.4 (dm, 4 F, ²J_PF = 98 Hz, CF₂); ³¹P NMR (202.4 MHz, CDCl₃, 298 K): δ [ppm] = −147.4 (tdm, ¹J_PF = 904 Hz, ¹J_PF = 891 Hz); IR ([cm⁻¹]): 2973 (w), 2942 (w), 1589 (vw), 1532 (w), 1388 (vw), 1373 (vw), 1310 (w), 1294 (w), 1265 (vw), 1208 (vs), 1179 (vs), 1134 (s), 1125 (s), 1098 (s), 1069 (m), 1010 (w), 960 (m), 869 (w), 815 (s), 777 (w), 760 (m), 719 (vs), 636 (w), 617 (vs), 580 (m), 532 (m), 495 (w), 468 (vw), 438 (vw), 428 (w); HRMS (ESI) m/z [M]⁺ calcd for C₂₄H₃₉CuNO: 420.2328, found: 420.2313; m/zFAP⁻ calcd for C₆F₁₈P: 444.9450, found: 444.9443; elemental analysis calcd (%) for C₃₀H₃₉CuF₁₈NOP: C 41.60, H 4.54, N 1.62; found: C 41.89, H 4.51, N 1.77.

Crystallographic details

Crystal data were collected on a Bruker X8 Apex-2 diffractometer with a CCD area detector and graphite monochromated Mo-Kα radiation or a Rigaku XtaLAB Synergy-DW diffractometer with an Hy-Pix-6000HE detector and monochromated Cu-Kα radiation equipped with an Oxford Cryo 800 cooling unit. Crystals were immersed in a film of perfluoropolyether oil on a glass fiber MicroMount™ (MiTeGen) and data were collected at 100 K. Images were processed with Bruker or CrySalis software packages and equivalent reflections were merged. Corrections for Lorentz-polarization effects and absorption were performed if necessary and the structures were solved by direct methods. Subsequent difference Fourier syntheses revealed the positions of all other non-hydrogen atoms. Structures were solved by using the ShelXTL software package.⁴⁰ All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were assigned to idealized geometric positions and were included in structure factors calculations.

Crystallographic data for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC 2444352 (1), 2444336 (3), 2444351 (5), 2444348 (6), 2444349 (7), 2444343 (10), 2444350 (11), 2444347 (12), 2444346 (16), 2444340 (17), 2444345 (19), 2444342 (20), 2444338 (21), 2444341 (23), 2444344 (24), 2444339 (26), 2444337 (27).

Data availability

The data supporting this article have been included as part of the manuscript and the ESI.† Crystallographic data are also deposited in the form of CIF files at the Cambridge Crystallographic Data Centre with reference number CCDC 2444352 (1), 2444336 (3), 2444351 (5), 2444348 (6), 2444349 (7), 2444343 (10), 2444350 (11), 2444347 (12), 2444346 (16), 2444340 (17), 2444345 (19), 2444342 (20), 2444338 (21), 2444341 (23), 2444344 (24), 2444339 (26), 2444337 (27).

Conflicts of interest

The authors declare no conflict to declare.

Acknowledgements

This work was supported by the Julius-Maximilians-Universität Würzburg.

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Footnote

† Electronic supplementary information (ESI) available: Crystallographic data and NMR spectra. CCDC 2444352 (1), 2444336 (3), 2444351 (5), 2444348 (6), 2444349 (7), 2444343 (10), 2444350 (11), 2444347 (12), 2444346 (16), 2444340 (17), 2444345 (19), 2444342 (20), 2444338 (21), 2444341 (23), 2444344 (24), 2444339 (26) and 2444337 (27). For ESI and crystallographic data in CIF or other electronic format see DOI: https://doi.org/10.1039/d5dt00904a

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