Themed collection In memory of Professor Kenneth Wade

This perspective describes the recent discovery and investigation of homopolar dihydrogen bonding, and focuses on the identification and characterisation of hydride–hydride interactions in compounds of the main group elements.

The structures of phosphine and thiolato- clusters of gold are summarised and a theoretical model which unites the broad structural properties is presented.

A carborane-fullerene dyad for organic field-effect transistors illustrates one of the many diverse areas of technology in which the special properties of these polyhedral boron clusters are being exploited.

The creation of the most emissive series of europium complexes is traced and examples given of their use in imaging.

The molecular structures of two dysprosium complexes of donor-functionalized pentadienyl ligands are described. Electronic structure calculations reveal that the W-shaped pentadienyl ligand strongly influences the orientation of the main magnetic axis of the ground Kramers doublets in both complexes.

The CH₂Cl₂ adduct of a Rh-PONOP-pincer complex is reported, that is also a latent low coordinate synthon for the synthesis of other species.

Ketiminoboranes, R₂CNB-R′₂, pioneered by Wade et al., are formally isoelectronic with allenes but undergo intramolecular cyclisation when R = 2-pyridyl to form heterocyclic boranes with N-donor capability.

Unusual complexes of ytterbium(II) stabilised by coordination to mixed O₄X₂-donor macrocyclic ligands (X = O, NH, S or Se) are described.

The synthesis and crystal structure of novel tin(II) ketoacidoximates and their utility in forming SnO particles and thin films with a high level of oxidation control under ambient conditions are described.

The Ligand Polyhedral Model (LPM) is applied to the carbonyl scrambling observed on the NMR timescale for the two cluster carbonyls [Rh₄(CO)₁₂] and [Rh₆(CO)₁₆].

The title complexes have been characterized for X = F by multinuclear NMR (including [¹H,¹⁹F]-HMBC) experiments, confirming that the observed ¹⁹F–¹H (and –¹³C) coupling occurs with chemical connectivity across C–H⋯F–C interactions, and their catalytic efficiencies for ethylene polymerization have been investigated.

An open cage triple-decker molecule with three planar rings almost parallel to each other (see the picture).

A novel, simplified synthesis of [Au₅Mes₅] and its use for deposition of halide free Au nanoparticles on SiO₂ and Al₂O₃.

Reactions of the vinylidene complexes [M(CCH₂)(PP)Cp′]PF₆ with NH₃ readily afford the acyclic amino carbene complexes [M{C(Me)NH₂}(PP)Cp′]PF₆ [M(PP)Cp′ = Fe(dppe)Cp, Ru(dppe)Cp, Ru(PPh₃)₂Cp, Ru(dppe)Cp*].

The synthesis and structures of 25 halide, separated ion pair, and hydride cyclopentadienyl iron bis(diphenylphosphino)ethane complexes are described.

New bis(phenolate)amine-supported neodymium borohydride complexes and their previously reported samarium analogues were tested as catalysts for the polymerisation of styrene and isoprene.

The aluminium reagent Al(NMe₂)₃ acts as a stoichiometric or catalytic reagent in dehydrogenic Si–N bond formation using amines and silanes. The observed catalytic rate law suggests a mechanism involving the silane component in the deprotonation of the amine.

Computational studies have been undertaken to investigate the electronic structures of six hetero-substituted borane cages, concluding that hypho-7,8-[S₂B₆H₉]⁻ is the only true hypho species in this series.

The iminoborylene complex [CpFe(PCy₃)(CO)(BNCMes₂)]⁺ undergoes MB metathesis reactivity with carbodiimides, resulting in FeB cleavage and the formation of isonitrile complexes.

The magnetic properties and ligand-field effects for quasi-linear iron(II) complexes are explored with the aid of theoretical models.

The H– on the adjacent carbon of the carboranylcarboxylate ligand is responsible for intramolecular interactions that stabilize the nuclearity of Cu(II) complexes.

An investigation of C-dimesitylboryl-ortho-carboranes, 1-(BMes₂)-2-R-1,2-C₂B₁₀H₁₀ (1 and 2), reveals that the carborane is the electron-acceptor and the mesityl group is the electron-donor in these dyads.

The 1,4-dioxane derivative of cobalt bis(dicarbollide) reacts with dialkylsulfides and triphenylphosphine to give the corresponding sulfonium and phosphonium derivatives.

MF₃·3H₂O (M = Al, Ga or In) react with neutral imine ligands under hydrothermal conditions to yield mer-trifluoro complexes with extensive H-bonding.

DFT calculations allied with experimental crystallographic and NMR results elucidate the energetics and the geometrical and ¹¹B nuclear shielding changes in the contrarotational fluxionality of [3,3-(PMe₂Ph)₂-closo-3,1,2-PtC₂B₉H₁₁] and confirm the incidence and identities of two stable rotational conformers.

Spectroelectrochemical studies show four accessible redox states on dyad 3 with the first oxidation process taking place at the Ru(II) centre and the second oxidation and first reduction processes at the porphyrin centre.

The {SB₉H₈(NC₅H₅)}-to-{Rh(dppe)} linkage is labilized upon protonation leading to a closo ↔ nido tautomerism; non-rigidity and higher Lewis acidity, induced by the proton, make possible the H₂ activation on the cationic rhodathiaborane.

A bis(2-methoxybenzene)-substituted disilazide pincer ligand coordinates to group 4 metal compounds to afford a conformationally flexible metallacycle.

From the reaction between BiCl₃ (1 equiv.) and LiN(SiMe₃)₂ (4 equiv.) and LH₂ (2 equiv.), where L = a tetraphenylporphyrin, TPP, an octaethylporphyrin, OEP and phsalen in THF the title compounds have been obtained I LiBiTPP₂, II LiBiOEP₂, and IIIA LiBi(phsalen)₂ and IIIB LiBi(phsalen)₂·THF.

In the presence of a bulky N-heterocyclic carbene, Zn(HMDS)₂ can be converted in to either a mononuclear amido/hydride complex or a tetranuclear hydride rich cluster depending on the hydride source and reaction conditions employed.

1,3-Bis(2,4,6-trimethylphenyl)triazenide anions act as bidentate ligands toward s-block metals; in the calcium derivative π-stacking of the aromatic rings leads to additional stabilization of the complex.

From hard to soft: The ion affinities of a large set of 33 Lewis acids towards hard and soft bases were examined with a unified isodesmic approach.

A model for understanding two isoelectronic matryoshka clusters based on a layer-by-layer electron count assignment is presented.

Donor complexes of the synthetically important lithium magnesiate LiMg(ⁿBu)₃ have been prepared and characterised.

The lowest energy Cp₂M₂B₃H₇ (M = Pd, Pt) and Cp₂M₂B₃H₇ (M = Rh, Ir) structures are analogous to the isoelectronic B₅H₁₁ and B₅H₉, respectively. Trigonal bipyramidal structures are found for the electron poorer Cp₂M₂B₃H₇ (M = Ru, Os, Mo, W, Ta) systems. Low energy Cp₂Re₂B₃H₇ structures include Re₂B₂ tetrahedra with the Re–Re edge capped by the third boron atom.

DFT calculations have shown that the α-reciprocal paired R₂²(8) H-bond interactions commonly found in the solid-state structures of pentaborate(1−) salts are strong (−21 kJ mol⁻¹ per H-bond).

Like the pieces of a jigsaw, maximum stability in clusters is achieved when electron density on metal and cage interlock.

A theoretical assessment of the degree of (anti)aromaticity in various borole compounds reveals distinct substituent effects.

Rare-earth metallacarborane alkyls have been prepared for the first time, which react with unsaturated organic molecules to give either mono- or di-insertion products depending on the nature of the substrates.

A hydroxyl group at the carbaborane cluster reduces exo-polyhedral C–C cleavage and enables reduction of carbaboranyl carboxylic acids and ketones to tertiary alcohols by organolithium reagents.

An unusual fragmentation of a triphosphaferrocene is observed, when it is reacted with Cu(I) halides. As a result, a large variety of different monomeric, dimeric and 1D and 2D polymeric coordination compounds are formed.

Charge-compensated nido-carboranyl thioether ligands [7-MeS-10-Me₂S-7,8-C₂B₉H₁₀] and [7,8-(MeS)₂-10-Me₂S-7,8-C₂B₉H₉] and tungsten carbonyl complexes on their base were prepared.

Copper pyromellitate complexes range from unusual discrete molecular ions to 2- and 3-dimensional polymeric networks with considerable ligand structural versatility.

Reactions of the dianions [^tBuN(E)P(μ-N^tBu)]₂²⁻ (E = Se,S) with M(I) reagents (M = Ag, Au) or HgCl₂ produce complexes of [^tBu(H)N(E)P(μ-N^tBu)₂P(E)N^tBu]⁻ with spirocyclic, macrocyclic or ladder structures.

The cleave and capture capacity of various bimetallic amido–alkyl mixtures is illustrated through reaction with the deprotonation sensitive N,N-dimethylphenylethylamine.

The molecular structures of the new copper phosphinimide complexes [Cu{μ-NPR₃}]₄ (1, R = NMe₂ and 2, R = Ph) reveal the presence of planar eight-membered {Cu₄N₄} rings, which have been shown by DFT calculation to be due to steric factors rather than electronics.

Both unisomerised and isomerised singly-metallated derivatives of 1,1′-bis(o-carborane) with both {Ru(arene)} and (CoCp} fragments have been prepared and characterised.

The reactivity of a Pt–Ir metal–metal bonded complex has been studied as a model for bimetallic Pt–Ir catalysts.

A model has been developed to reliably predict the configuration of the triphenylphosphine rotor of stereogenic metal complexes [M(η⁵-C₅H₅)(PPh₃)(L¹)(L²)].

The reactions of HCCBMIDA (BMIDA = B(O₂CCH₂)₂NMe) with a range of ruthenium complexes examples of σ-alkynyl, σ-alkenyl and vinylidene complexes bearing 4-coordinate boron substituents.

[Fe₄(CO)₁₀(κ²-dppn)(μ₄-O)]²⁻ reduces protons and DFT calculations support the sequential formation of hydride and dihydrogen ligands at the unique iron centre.

Oxidation of group 14 heteroborates [GeB₁₁H₁₁]²⁻ and [SnB₁₁H₁₁]²⁻ yields a symmetrical dimer exhibiting a Ge–Ge bond or an unsymmetrical dimer bearing an Sn–B bond.

A general synthetic route to water-soluble PEG-supported organotrifluoroborates has been developed. In the presence of air and catalytic amounts of Pd(OAc)₂, the PEG-supported organotrifluoroborates undergo homo-coupling reactions smoothly at room temperature.

Metal contamination of water is a serious challenge faced by environmental chemists, but there is also economic value in the removal of metals for recycling or extraction.

We report the synthesis of new A₄O₄Se₃ (A = rare earth element) materials and identify three new structure types (β, γ, δ).

Effects on the NMR spectra of a paramagnetic metal ion are clearly observed by comparing identical sandwich molecular structures of diamagnetic [3,3′-Co(1,2-C₂B₉H₁₁)₂]⁻ with paramagnetic [3,3′-Fe(1,2-C₂B₉H₁₁)₂]⁻.

The utilisation of the PNP iridium pincer complex [Ir(PNP)(COE)][BF₄] [PNP = 2,6-bis{(di-tert-butylphosphino)methyl}pyridine; COE = cyclooctene] in the sp³ C–H activation of methyl propanoate and other related esters was explored.

In a series of [Ru(bpy)₂(C^N)][PF₆] complexes with a variety of functionalities in the cyclometallating ligand, the absorption response is enhanced considerably by the introduction of a 4-C₆H₄P(O)(OEt)₂ anchoring domain in the C^N pyridine ring.

8-oxonium derivatives of iron bis(dicarbollide)(-I) were synthesized and their reactivity towards various nucleophiles was studied.

The phosphine unit of cationic thio- and seleno-phosphonium complexes exchange via a S_N2-type exchange process.

Benzannulated 9aneP₃ macrocycles have been prepared by two different routes using a single [Mn(CO)₃]⁺ template.

Inelastic X-ray scattering techniques enhance chemical speciation by X-ray absorption fine structure (XAFS) spectroscopy and open up application of X-ray free electron lasers to observe chemical transformations.