Three-Coordinate Nickel(I) Complexes Stabilised by Six-, Seven- and Eight-Membered Ring N-Heterocyclic Carbenes: Synthesis, EPR/DFT Studies and Catalytic Activity

被引：81

作者：

Page, Michael J. ^{[1
]}

Lu, Wei Y. ^{[2
]}

Poulten, Rebecca C. ^{[1
]}

Carter, Emma ^{[2
]}

Algarra, Andres G. ^{[3
]}

Kariuki, Benson M. ^{[2
]}

Macgregor, Stuart A. ^{[3
]}

Mahon, Mary F. ^{[1
]}

Cavell, Kingsley J. ^{[2
]}

Murphy, Damien M. ^{[2
]}

Whittlesey, Michael K. ^{[1
]}

机构：

[1] Univ Bath, Dept Chem, Bath BA2 7AY, Avon, England

[2] Cardiff Univ, Sch Chem, Cardiff CF10 3AT, S Glam, Wales

[3] Heriot Watt Univ, Inst Chem Sci, Edinburgh EH14 4AS, Midlothian, Scotland

来源：

CHEMISTRY-A EUROPEAN JOURNAL | 2013年 / 19卷 / 06期

基金：

英国工程与自然科学研究理事会;

关键词：

CC coupling; density functional calculations; EPR spectroscopy; N-heterocyclic carbenes; nickel; CROSS-COUPLING REACTIONS; KUMADA-TAMAO-CORRIU; H BOND ACTIVATION; POLARIZATION FUNCTIONS; ELECTRONIC-STRUCTURE; PALLADIUM COMPLEXES; MOLECULAR-STRUCTURE; METAL-COMPLEXES; ARYL CHLORIDES; BASIS-SETS;

D O I：

10.1002/chem.201202950

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

Comproportionation of [Ni(cod)2] (cod=cyclooctadiene) and [Ni(PPh3)2X2] (X=Br, Cl) in the presence of six-, seven- and eight-membered ring N-aryl-substituted heterocyclic carbenes (NHCs) provides a route to a series of isostructural three-coordinate NiI complexes [Ni(NHC)(PPh3)X] (X=Br, Cl; NHC=6-Mes 1, 6-Anis 2, 6-AnisMes 3, 7-o-Tol 4, 8-Mes 5, 8-o-Tol 6, O-8-o-Tol 7). Continuous wave (CW) and pulsed EPR measurements on 1, 4, 5, 6 and 7 reveal that the spin Hamiltonian parameters are particularly sensitive to changes in NHC ring size, N substituents and halide. In combination with DFT calculations, a mixed SOMO of 3dz2 and 3dx2y2 character, which was found to be dependent on the complex geometry, was observed and this was compared to the experimental g values obtained from the EPR spectra. A pronounced 31P superhyperfine coupling to the PPh3 group was also identified, consistent with the large spin density on the phosphorus, along with partially resolved bromine couplings. The use of 1, 4, 5 and 6 as pre-catalysts for the Kumada coupling of aryl chlorides and fluorides with ArMgY (Ar=Ph, Mes) showed the highest activity for the smaller ring systems and/or smaller substituents (i.e., 1>4 approximate to 6 >> 5).

引用

页码：2158 / 2167

页数：10

共 137 条

[1] Efficient aryl-(hetero)aryl coupling by activation of C-Cl and C-F bonds using nickel complexes of air-stable phosphine oxides [J].