The Reaction Pathway Leading to Dinuclear Rhodium and Iridium Complexes from Alkyne-Containing Bisphosphine Ligands

A mechanistic study of a series of dinuclear complexes produced by the complexation of alkyne-containing bisphosphine ligands with Ir and Rh has been performed by experimental analysis as well as density functional theory (DFT) calculations. The key process is oxidative cyclization involving two metals and two alkyne-containing ligands 1. The related alkyne-bridged dimer 7, considered as an intermediate, was determined using X-ray measurements. The DFT calculation supported that the core metals alter the reorganization pathways from alkyne-bridged dimer, leading to the unique structures 4 and 5.