Ionophilic Ru-SNS Complexes as Dual-Function Catalysts for CO 2 Hydrogenation and Formic Acid Dehydrogenation

This work presents homogeneous Ru complexes containing sulfur-based ionophilic ligands that exhibit high dual catalytic activity for CO₂ hydrogenation and formic acid dehydrogenation under mild conditions. Indeed, the ionophilic [RuCl₂(SNS)(PPh₃)] complexes promote the reduction of CO₂ to formate using DBU as a base, either in organic solvents (CH₃CN or CH₃CN/THF mixture, achieving TOFs of up to 1500 h^-1) or in ionic liquids ([BMIm][NTf₂], [OMIm][NTf₂]) at 80 °C and 40 bar (20 bar CO₂, 20 bar H₂). Additionally, independent reactions demonstrated that formic acid can be dehydrogenated with TONs of up to 1540 at the same temperature. Notably, one-pot recycling experiments revealed that the ionophilic Ru complexes are also capable of promoting CO₂ hydrogenation to formate and its subsequent dehydrogenation at 80 °C, providing evidence that these ionophilic Ru complexes are active sulfur-based catalysts for enabling a versatile cycle of hydrogenation/dehydrogenation reactions.