Rhodium nitrosyl catalysts for CO₂ hydrogenation to formic acid under mild conditions

摘要

A new synthetic protocol for catalysing CO₂ hydrogenation to formic acid under mild conditions is reported, and the CO₂ hydrogenation is efficiently achieved by dcpe-rhodium-nitrosyl catalyst precursors, Rh(NO)(dcpe) (1) (dcpe?=?1,2-dicyclohexylphosphinoethane) and Rh(III)(NO)(dcpe)Cl₂ (2). The catalytic activity of 1 is noteworthy for being able to proceed in the absence of protic conditions. Compound 2 is characterized by NMR, IR and X-ray crystallography. In particular, 2 is observed to bear a bent NO ligand with a Rh–N–O angle of 115.7(3)°, representing one of the smallest M–N–O angles known. Copyright ? 2012 John Wiley & Sons, Ltd.