Impact of Ligand Modification on Structures and Catalytic Activities of Chelating Bis-Carbene Rhodium(I) Complexes

A series of novel chelating N-heterocyclic bis-carbene rhodium(I) complexes based on 1,2,4-triazoles, benzimidazoles, and imidazoles with varying bridge length and N substituents has been synthesized. In addition to their structural characterization, their catalytic activity in the hydrosilylation of 4-fluoroacetophenone with diphenylsilane has been examined. The results reveal that selectivities and turnover frequencies (TOFs) are influenced by bridge length, steric demand of the N substituents, and electronic properties of the heterocycle.