An unusually static, sterically hindered silver bis(N-heterocyclic carbene) complex and its use in transmetalation

A dimeric silver complex of the bulky bis(N-heterocyclic carbene) ligand 1,1'-dimesityl-3,3'-methylenediimidazol-2,2'-diylidene exhibits a surprisingly static structure in solution, due to a favorable chelate ring conformation, yet serves as a convenient transmetalation reagent for the formation of a new (2)(K)-bis(NHC) rhodium(I) complex. The latter complex demonstrates a strong influence of N-substituent steric bulk on the bis(NHC) binding mode.