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, [(η 6 ‐benzyldimethylamine)Ru(PTA)Cl 2 ]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. 1 H ‐and 13 C‐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 31 P spectra.