Synthesis and characterization of rhodium, iridium, and palladium complexes of a diarylamido-based PNSb pincer ligand

Abstract

A new diarylmido-based pincer proto ligand (^iPrPN^HSb^Ph) with one –PPrⁱ₂ and one –SbPh₂ side donor has been synthesized. Three complexes of its amido form were prepared using standard metalation techniques: (^iPrPNSb^Ph)PdCl, (^iPrPNSb^Ph)RhCO, and (^iPrPNSb^Ph)Ir(COE), where COE = cis-cyclooctene. These complexes were compared with their previously reported analogs incorporating a –PPh₂ side donor in place of –SbPh₂. The –SbPh₂ donor arm is less donating towards the metal and is less strongly trans-influencing, based on the structural and IR spectroscopic analysis of the Rh complexes. The redox potential of the Pd complexes is only marginally affected by the change from –PPh₂ to –SbPh₂. (^iPrPNSb^Ph)Ir(COE) proved to be a slower and less selective catalyst in the dehydrogenative borylation of terminal alkynes (DHBTA) than its –PPh₂ analog.