Synthesis, characterization and reactivity of iridium pincer complexes

Using the pincer-ligated iridium fragment [((POCOP)-P-R)Ir] ((POCOP)-P-R = 2,6-bis(di-tert-butyl-phosphonito) benzene or 2,6-bis(di-iso-propyl-phosphonito)benzene), a range of complexes with widely varying steric and electronic properties, have been synthesized and studied. The complexes include the novel Ir species ((POCOP)-P-tBu)Ir(L) (L= MeCN (2), pyridine (3), 2,4,6-triphenylphosphinine (11)), ((POCOP)-P-iPr)Ir(H)(CI)(L) (L = PPh3 (7), PCy3 (8), 2,4,6-triphenylphosphinine (12)) and ((POCOP)-P-iPr)Ir(L) (L = PPh3 (9), PCy3 (10), 2,4,6-triphenylphosphinine (13)). Complex 4, ((POCOP)-P-tBu)Ir(PPh3), serves as a convenient source of the latent WI), 14 -electron species [(`BuPOCOP)Irl, and is susceptible to ligand exchange chemistry; reactions with MeCN and pyridine afford complexes 2 and 3, respectively. Complexes 11-13 represent rare examples of phosphinine-ligated iridium complexes and are the first examples of any pincer -supported metal complex exhibiting coordination to a phosphinine. The solid-state structure of 11 was determined by single crystal X-ray diffraction studies. (C) 2017 Elsevier Ltd. All rights reserved.