Tin-Ruthenium Cooperative Catalyst for Disproportionation of Formic Acid to Methanol

The disproportionation of formic acid to methanol and CO2 offers a renewable route to methanol avoiding the use of high-pressure H-2. Previous studies have identified competent transition-metal catalysts that nonetheless experienced unsatisfactory methanol selectivity because of competing formic acid dehydrogenation, motivating further catalyst improvement. Herein we report a bimetallic cooperative catalyst based on tin(II) oxide and a ruthenium complex for the disproportionation of formic acid to methanol. The diruthenium complex [(Cp*Ru)(2)(mu-NPh)(mu-CH2)] (Cp* = eta(5)-C5Me5) combined with tin(II) oxide gave methanol (and methyl formate) in up to 28% selectivity and 191 turnovers under optimized conditions. The isolation of a Ru2Sn heterotrimetallic complex [{Cp*Ru(CO)(2)}(2)Sn(O2CH)(2)] from a catalytic reaction mixture indicated the generation of an active Ru-Sn bonded species in situ. Reaction pathways involving a tin(II) formate unit supported by Ru-Sn bonds are discussed with the aid of computational results.

Automated summary

A bimetallic cooperative catalyst based on tin(II) oxide and a ruthenium complex has been developed for the disproportionation of formic acid to methanol, achieving up to 28% selectivity and 191 turnovers under optimized conditions. The generation of an active Ru-Sn bonded species in situ was indicated by the isolation of a Ru2Sn heterotrimetallic complex from a catalytic reaction mixture.