Synthesis, Structure, and Catalytic Activity of Cyclometalated Iridium Complexes with a Bidentate POC Ligand

Abstract

AbstractSynthesis, characterization and catalytic activity of cyclometalated iridium complexes with a bidentate POC ligand is presented. Metalation of POC‐H (di‐tert‐butyl(phenoxy)phosphane) with [Ir(COD)Cl]2 proceeded rapidly at room temperature and afforded mixture of (POC)(POC‐H)IrHCl (1 a) and (POC)(COD)IrHCl (1 b), from which complexes (POC)(L)IrHCl where L=PPh3 (1 c), bipyridine (1 d) and [2,2′‐bipyridine]‐6,6′‐diol (1 e) were prepared through ligand exchange. The compounds were tested in acceptorless dehydrogenation of 1‐phenylethanol and transfer dehydrogenation of ethanol in a context of comparison with pincer counterparts (POCOP)IrHCl and (PCN)IrHCl. An attempt to prepare a dihydride complex from 1 e led to dimeric complex [(POC)(bipy‐diol−)IrH]2 (3) that could explain the low activity of 1 e. DFT studies provided insight into POC‐H vs POCOP‐H metalation mechanism.