Flash Communication: Ir Complexes with a PhN(CH2CH2PiPr2)2 Pincer Ligand for Reversible CO2 Hydrogenation

The pincer ligand PhN(CH 2 CH 2 P i Pr 2 ) 2 ( iPr PN Ph P) was treated with [Ir(coe) 2 (μ-Cl)] 2 (coe = cyclooctene) under H 2 to generate ( iPr PN Ph P)IrH 2 Cl ( 1 ). Reaction of 1 with LiBHEt 3 formed ( iPr PN Ph P)IrH 3 ( 2 ). The solid-state structures of 1 and 2 were determined. Compound 2 catalyzes CO 2 hydrogenation to formate and formic acid dehydrogenation but gives inferior performance to systems with RN(CH 2 CH 2 P i Pr 2 ) 2 (R = H or Me) ligands, demonstrating the importance of the substituent on the nitrogen donor.