A low-valent dinuclear ruthenium diazadiene complex catalyzes the oxidation of dihydrogen and reversible hydrogenation of quinones.

The dinuclear ruthenium complex [RuH(μ-H)(Medad)(dbcot)] contains a 1,4-dimethyl-diazabuta-1,3-diene (Medad) as a non-innocent bridging ligand between the metal centers to give a [Ru(Medad)] core. In addition, each ruthenium is bound to one dibenzo[,]cyclooctatetraene (dbcot) ligand. This Ru dimer converts H to protons and electrons. It also catalyzes reversibly under mild conditions the selective hydrogenation of vitamins K and K to their corresponding hydroquinone equivalents without affecting the C[double bond, length as m-dash]C double bonds. Mechanistic studies suggest that the [Ru(Medad)] moiety, like hydrogenases, reacts with H and releases electrons and protons stepwise.