Iridium Complexes of a Bis(-pyrrolyl)boryl/Bis(phosphine) PBP Pincer Ligand.

This work reports the synthesis of a bis(pyrrolylphosphino)phenyl borane (PBP)Ph () and its incorporation of Ir by metal insertion into B-Ph to afford the dipyrrolylboryl/bis(phosphine) pincer complex (PBP)Ir(Ph)Cl (). Hydrogenolysis of afforded (PBP)Ir(H)Cl (). Compound was converted into (PBP)IrCl () via reaction with -chlorosuccinimide, and exposure of to CO produced (PBP)IrCl(CO) (). Compounds and were converted into their analogs (PBP)IrI () and (PBP)IrI(CO) () via metathesis with MeSiI, respectively. Treatment of either or with Li[HAl(OBu)] under H resulted in the formation of (PBP)IrH (), with traces of as a persistent impurity. Attempts to access via the reaction of with NaBH in isopropanol led to the loss of boron from the pincer and isolation of LIrH (, L = 2-diisopropylphosphinopyrrole). Compounds , , and were examined as catalysts for alkane transfer dehydrogenation but displayed only the modest activity. Solid-state structures of and were established by X-ray crystallography.