Catalytic Ionic Hydrogenation of Ketones by {[Cp*Ru(CO)₂]₂(μ-H)}⁺

{[Cp*Ru(CO) 2 ] 2 (μ-H)} + OTf − functions as a homogeneous catalyst precursor for hydrogenation of ketones to alcohols, with hydrogenations at 1 mol % catalyst loading at 90 °C under H 2 (820 psi) proceeding to completion and providing >90% yields. Hydrogenation of methyl levulinate generates γ-valerolactone, presumably by ring-closing of the initially formed alcohol with the methyl ester. Experiments in neat Et 2 C═O show that the catalyst loading can be <0.1 mol % and that at least 1200 turnovers of the catalyst can be obtained. These reactions are proposed to proceed by an ionic hydrogenation pathway, with the highly acidic dihydrogen complex [Cp*Ru(CO) 2 (η 2 -H 2 )] + OTf − being formed under the reaction conditions from reaction of H 2 with {[Cp*Ru(CO) 2 ] 2 (μ-H)} + OTf − .