Homogeneous Catalytic Formic Acid Dehydrogenation in Aqueous Solution using Ruthenium Arene Phosphine Catalysts

In this work, we studied catalytic formic acid dehydrogenation with a homogeneous RAPTA type precatalyst in aqueous solution. The effects of an amino group, attached to the arene, and the impact of a second equivalent of 1,3,5‐triaza‐7‐phosphaadamantane (PTA) added in situ to the reaction were evaluated. The initial compound, [(η6‐benzyldimethylamine)Ru(PTA)Cl2]Cl (3), was synthesized and proved to be moderately active for selective formic acid dehydrogenation. The addition of a second equivalent of PTA at the beginning of the reaction significantly improved the catalytic performance. The activation energies for both catalytic systems were assessed via an Arrhenius plot. 1H ‐and 13C‐NMR spectroscopy was used to follow the course of the reaction online and verified complete consumption of substrate. A triplet signal was observed in the hydride region along with its corresponding coupling counterpart in 31P spectra.