Synthesis of bis N-heterocyclic carbenes,derivatives and metal complexes

A method for the synthesis and isolation of 1,1′-methylene-bis-(3-aryl-imidazol-2-ylidene) ligands, aryl = 2,6-diisopropyl-phenyl (DiPP), L^DiPP, mesityl (mes), L^mes, is reported, which provides synthetically useful quantities of high purity. Derivatisation of L^DiPP with chalcogenides gave the adducts L^DiPPE₂, E = S, Se, Te. Reaction of L^DiPP with Pd(tmeda)Me₂], Pt(μ-SMe₂)Me₂]₂, Ir(1,5-COD)(μ-Cl)]₂/KPF₆ and NiBr₂(dme)] gave Pd(L^DiPP)Me₂] (1), Pt(L^DiPP)Me₂] (2), Ir(L^DiPP)(1,5-COD)](PF₆) (3) and Ni(L^DiPP)Br₂] (4), respectively. The latter was reduced in the presence of CO to Ni(L^DiPP)(CO)₂] (5). The structures of L^mes, L^DiPPTe₂, and 1–5 are also reported.