Synthesis and characterization of rhodium, iridium, and palladium complexes of a diarylamido-based PNSb pincer ligand†
Abstract
A new diarylmido-based pincer proto ligand (iPrPNHSbPh) with one –PPri2 and one –SbPh2 side donor has been synthesized. Three complexes of its amido form were prepared using standard metalation techniques: (iPrPNSbPh)PdCl, (iPrPNSbPh)RhCO, and (iPrPNSbPh)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. (iPrPNSbPh)Ir(COE) proved to be a slower and less selective catalyst in the dehydrogenative borylation of terminal alkynes (DHBTA) than its –PPh2 analog.