Themed collection Earth Abundant Element Compounds in Homogeneous Catalysis

Welcome to this themed issue of Dalton Transactions in the area of earth abundant element (EAE) compounds in homogeneous catalysis.

Oxidative cyclization of alkynes and imines with nickel(0) is a key step in multicomponent coupling and cycloaddition reactions to give nitrogen-containing organic compounds.

This perspective provides an overview of the recent advancements in earth abundant element-based catalysts for alkene hydrofunctionalisation.

Complexes [Cu(I)(2,4-dimethylphenoxy)₂]⁻ (A) and [Cu(II)(2,4-dimethylphenoxy)₂(p-tolyl)]⁻ (B) were observed by in situ ESI-MS analysis of the ligand free copper(I)-catalyzed C–O coupling reaction using Cs₂CO₃ under the catalytic reaction conditions.

Air-stable Cu(II) species are competent precatalysts in the aerobic oxygenation of phenols into ortho-quinones.

Bis(trimethylsilyl)amide derivatives of the group 1 elements (Li, Na, K) are competent pre-catalysts for the dehydrocoupling of Me₂NH·BH₃via the formation of intermediates containing [H₃BNMe₂BH₂Me₂N]⁻ anions.

Simple cobalt compounds engage in ammonia borane dehydrocoupling and transfer hydrogenation.

Al(III) catalysts at concentrations as low as 0.001% ring-open cyclohexene oxide to yield high molecular weight polyether with narrow dispersity.

High regioselectivity was achieved in the Cu(I)-catalyzed borylation of internal propargylic alkynes with a silyl substituent to afford multifunctionalized alkenylboron compounds.

Nickel(II) hydroxo compounds supported by an electron rich PCP pincer ligand are active catalysts for the selective hydration of a variety of nitriles at low catalyst loadings and mild conditions.

New findings for the water-oxidizing activity of [(L)Cu^II(NO₃)], (L = (E)-3-(pyridin-2-yldiazenyl)naphthalen-2-ol (HL)) under both electro-water oxidation conditions and in the presence of cerium(IV) ammonium nitrate are reported.

New titanium(IV) complexes having two bidentate β-iminoethyl-spiro[4,5]decan-6-onato ligands with various N-aryl substituents have been synthesized.

A series of titanium pyridonate complexes have been synthesized under very mild reaction conditions from a common precursor, Ti(NMe₂)₄. These complexes have been explored as initiators for the ring-opening polymerization of rac-lactide and ε-caprolactone and have proven to be competitive with leading titanium initiators.

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.

Despite decades of thorough mechanistic investigations, it is still hard to predict the activity of a novel olefin polymerisation catalyst, even when the precursor is a well-defined molecular entity. Kinetic studies using quenched-flow methods can help to understand why.

Magnesium and zinc complexes derived from binaphthyl-based iminophenolate ligands efficiently initiated the ring-opening polymerization of rac-lactide and α-MeTMC, with the highest heteroselectivity (P_r = 0.84) or regioselectivity (X_reg = 0.98) obtained for the zinc complex.

Fe/Mn complexes of ethylene cross-bridged homocyclen catalyze oxygen atom transfer and hydrogen abstraction.

High activity for the catalytic oxidation of 3,5-di-tert-butylcatechol was achieved with complexes of ligands that stabilize the biomimetic Cu^II μ-thiolate complex, hinting at a similarity with the required Cu-oxo intermediates.

Structurally diverse phosphinophenolate Zn(II) heteroleptic and homoleptic compounds are reported, some of which efficiently mediate the controlled ROP of lactide, ε-caprolactone and trimethylene carbonate under living and immortal conditions.

Rival mechanistic pathways for CC bond activation in aluminium-catalysed hydroamination: computational mechanistic analysis reveals that a catalytically relevant [(pda)Al(NHR)] compound promotes hydroamination through a stepwise σ-bond insertive mechanism with turnover-limiting aminolysis.

A study of the dehydrogenation of dimethylamine borane using different titanocene(III) complexes with 2-phosphinoaryloxide ligands is presented.

Magnesium complexes capable of rac-lactide polymerization in both the melt and in solution at elevated temperatures were synthesized. End-group analysis by MALDI-TOF showed both linear and cyclic PLA.

Covalent tethering of a P₂N₂ ligand to a planar, azide-terminated glassy carbon electrode surface was accomplished using a Cu^I-catalyzed “click” reaction, followed by metallation with Ni^II.

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.

A series of fluorophosphonium salts, [R₃PF][X] (R = alkyl or aryl; X = FB(C₆F₅)₃, [B(C₆F₅)₄]), have been prepared by reactions of phosphine/borane frustrated Lewis pairs (FLPs) with XeF₂ or difluorophosphoranes with [Et₃Si][B(C₆F₅)₄].

The preparation, characterization and properties of a series of 8-hydroxy quinolinolate complexes of Ti(IV), Al(III) and Zn(II) are presented. The complexes are active initiators for rac-lactide polymerizations: their performances are compared.

Nickel POCOP-pincer hydride complexes react with phenylacetylene to afford alkenyl complexes whereas the palladium analogues give alkynyl complexes.

Use of various combinations of [VOCl₃], LiOt-Bu and p-tert-butylcalix[6]areneH₆ affords vanadyl complexes capable of ethylene homo-(co-)polymerization.

A new salicylaldiminato tin(II) catalyst system having alkoxy side chains has been developed and shown to effectively polymerize L-lactide and ε-caprolactone giving cyclic PLA and cyclic PCL, respectively.

Finely tuned substituents within ligands control the catalytic performance of the corresponding complex precursors, tailoring resulting polyethylenes.

Reported is a rare example of the use of monophosphines in iron catalysed Negishi cross-coupling. Substrate scope in terms of alkyl bromide and diaryl zinc reagent is explored.

The amphipolar iron(III) corrole 1-Fe is one of the most efficient catalysts for the decomposition of peroxynitrite, the toxin involved in numerous diseases.

A series of homochiral (Cu₂)₂L₄ lantern cages have been synthesized, which can promote cyclopropanation with up to 99 : 1 diastereoselectivity.

Reaction of the pro-ligands α,α,α′,α′-tetra(3,5-di-tert-butyl-2-hydroxyphenyl-p-(or -m-)xylene-para-(or -meta-)tetraphenol with [MCl₅] (M = Nb, Ta) or [Nb(O)Cl₃(NCMe)₂] afforded complexes capable of the ROP of e-caprolactone at high temperature.

The {CH(PPh₂NSiMe₃)(PPh₂S)}⁻ ligand has been used for the synthesis of divalent and trivalent rare-earth borohydride complexes. These compounds enable the ring-opening polymerization (ROP) of ε-caprolactone (CL) and trimethylene carbonate (TMC).

V(N-2,6-X₂C₆H₃)Cl₂(O-2,6-R₂C₆H₃) (X = Cl, F; R = Me, F) showed remarkable activity in ethylene polymerisation and the copolymerisation with norbornene in the presence of Et₂AlCl.

A titanium mono(formamidinate) complex catalyzes the hydroaminoalkylation of unactivated, sterically demanding, disubstituted alkenes and styrenes with secondary amines.

Yttrium complexes – efficient precatalysts for intermolecular olefin hydrophosphination and hydroamination.

Tetranuclear alkoxide 3 with a saddle-shaped Zn₄O₄ conformation was an active initiator for living ROP of ε-caprolactone and β-butyrolactone.

A series of alkyl organoaluminium complexes based on bulky heteroscorpionate ligands were designed as catalysts for the ring-opening polymerisation of cyclic esters.

A series of “diamond-core” bridged dinuclear first-row transition metal complexes with the dinucleating ligand DPFN are prepared and characterized.

An iron ATH catalyst is slowly transformed into an inactive, achiral iron complex under catalytic conditions.