Hydrogenation of an iridium-coordinated imidazol-2-ylidene ligand fragment.

An iridium complex featuring a metalated lutidine-derived CNP ligand reacts with KOtBu to yield a dimeric species with the two metal centers bound to the opposite ligands through the CHN arms. Furthermore, reaction with H2 in the presence of KOtBu of the same iridium derivative results in the hydrogenation of the -CH[double bond, length as m-dash]CH- imidazolylidene moiety of the complex. NMR spectroscopy monitoring of the latter reaction supports the initial formation of a dihydride iridium complex containing an imidazolylidene ligand fragment that is hydrogenated after prolonged reaction time.