Synthesis of a Mixed Silylene–Carbene Chelate Ligand from an N-Heterocyclic Silylcarbene Mediated by Nickel

作     者：Gengwen Tan Matthias Driess Xinping Wang 

作者单位：Department of Chemistry Nanjing University Department of Chemistry Technische Universitt Berlin 

会议名称：《中国化学会第九届全国无机化学学术会议》

会议日期：2015年

学科分类：081704[工学-应用化学] 07[理学] 070304[理学-物理化学(含∶化学物理)] 08[工学] 0817[工学-化学工程与技术] 0703[理学-化学] 

关 键 词：silylene main group chemistry N-heterocyclic carbene homogeneous catalysis cross-coupling reaction 

摘      要：N-heterocyclic carbenes（NHCs） represent one of the most widely utilized supporting ligands in transition metal（TM） chemistry in the last decades.[1] These complexes have exhibited numerous superior activities in comparison to phosphine complexes owing to the stronger σ donor ability of NHC ligands.[2] Whereas, the heavy homologs of NHCs, the N-heterocyclic silylenes（NHSis） are emerging as a novel class of versatile steering ligands in the coordination chemistry of the transition metals, and their complexes have already shown remarkable features in small molecule activation and as precatalysts for various types of organic transformations.[3] Therefore, combining these two ligand types in one chelate molecule might enable new coordination features at TMs. Moreover, the presence of both strong σ-donating moieties might facilitate the coordination and dissociation of other ligands thereby improving the reactivity or catalytic performance of respective TM *** I present the unexpectedly facile formation of the first mixed NHSi-NHC chelate complex[L1Si:（CH2）（NHC）]NiBr2 2 [L1 = CH（Me C=NAr）2, Ar = 2,6-iP r2C6H3;NHC =3,4,5-trimethylimidazol-2-yliden-6-yl] through the hydrogen atom migration from the silicon atom to the exocyclic methylene group in L2Si（H）（CH2）NHC [L2 = CH（C=CH2）（CMe）（NAr）2, Ar = 2,6-iPr2C6H3;NHC =3,4,5-trimethylimidazol-2-yliden-6-yl] mediated by Ni Br2. The analogous reduction of 2 in the presence of1,2-bis（dimethylphosphino）ethane（DMPE） furnishes the first mixed NHSi-NHC（DMPE）Ni0 complex 3. Moreover,complex 2 shows a high catalytic activity for Kumada-Corriu-type cross-coupling reactions.[4]