Copper Boryl Complexes Research Articles

Stability and decomposition of copper(i) boryl complexes: [(IDipp)Cu–Bneop], [(IDipp*)Cu–Bneop] and copper clusters

Synthesis and characterisation of NHC copper boryl complexes [(NHC)Cu–Bneop] and their decomposition to low-valent copper clusters.

Copper, Boron and Vinyl Epoxides: from 1,4-Diols to Cyclopropylboronates.

Herein we describe the reactivity found between vinyl epoxides and catalytically generated copper-boryl complexes. By tuning the substituents of the alkene and/or the reaction conditions, 1,4-diols, allylic alcohols or cyclopropylboronates can be prepared. The stereochemical information of the vinyl epoxide is transferred to the products with high levels of stereocontrol.

Syntheses, Structures, and Reactivity of NHC Copper(I) Boryl Complexes: A Systematic Study

Five novel NHC copper(I) boryl complexes were synthesized by B–B activation via σ-bond metathesis of symmetrical tetraalkoxy and unsymmetrical dialkoxy diamino diborane(4) derivatives. Despite their low stability, the NHC copper boryl complexes were thoroughly characterized spectroscopically and structurally. Variation of the NHC ligand (ItBu or Me2IiPr) as well as of the boryl ligand (Bpin, Bdmab, or BiPrEn) allowed, for the first time systematically, a study in such complexes of the dependence on steric encumbrance. For sterically more demanding ligand combinations, mononuclear linear complexes were obtained, while with less demanding ligand combinations, dimeric dinuclear complexes with two bridging μ-boryl ligands were obtained, exhibiting extremely short Cu···Cu distances (<2.26 A). The decomposition of all these complexes was found to proceed via a common pathway, leading ultimately to elemental copper, the free NHC ligand, and the respective symmetrical diborane(4) derivative. The rate of decomposi...

Elusive Phosphine Copper(I) Boryl Complexes: Synthesis, Structures, and Reactivity

We report the first isolation of phosphine copper boryl complexes—species pivotal to numerous copper-catalyzed borylation reactions. The reaction of diboron(4) derivatives with copper tert-butoxide complexes of phosphine ligands allows the isolation of the dimeric μ-boryl-bridged Cu(I) complexes [(iPr3P)Cu–Bdmab]2 (4) and [(C6H4(Ph2P)2)Cu–Bpin]2 (6) with Cu···Cu distances of 2.24–2.27 A (dmab = (NMe)2C6H4, pin = (OCMe2)2)). A slightly more sterically demanding boryl ligand furnishes the unprecedented multinuclear copper boryl complex [(iPr3P)2Cu8(B(iPrEn))3(OtBu)3] (5), a potential intermediate of the decomposition of an initial Cu(I) boryl complex (iPrEn = (NiPr)2C2H4). All complexes were characterized by single-crystal X-ray diffraction, NMR spectroscopy, and elemental analysis. DFT computations support the nature of these unique complexes and give insight into their electronic structures.

Synthesis and further reactivity studies of some transition metal gallyl complexes

Reactions of the anionic gallium(I) heterocycle salt, [K(tmeda)][Ga(DAB)] (DAB = {N(Dip)C(H)} 2; Dip = C 6H 3Pr i 2-2,6), with a series of groups 6–9 and 11 metal halide complexes have given rise to the metal gallyl complexes, [CpCr(IMes){Ga(DAB)}] (IMes = :C{(Mes)NC(H)} 2; Mes = mesityl), [M(tmeda){Ga(DAB)} 2] (M = Mn, Fe or Co) and [Cu(dppe){Ga(DAB)}] (dppe = 1,2-bis(diphenylphosphino)ethane). The majority of the complexes have been crystallographically characterized. The reactivity of the previously reported copper(I) gallyl complex, [(IPr)Cu{Ga(DAB)}] (IPr = :C{(Dip)NC(H)} 2), towards a variety of unsaturated substrates has been explored. Three crystallographically characterized complexes have arisen from this phase of the study, viz. [(IPr)CuC CPh], [(IPr)Cu{Ga(DAB)}(C NBu t)] and [(IPr)Cu{κ 1-OC(O)C( CNHDip)(NHDip)}]. The results of these investigations show that the reactivity of [(IPr)Cu{Ga(DAB)}] is significantly different to that of related copper boryl complexes.