Reductive Dimerization of Nitric Oxide to trans-Hyponitrite in the Coordination Sphere of a Dinuclear Ruthenium Complex

During the reaction of the coordinatively unsaturated compound [Ru₂(CO)₄(μ-H)(μ-PBu^t₂)(μ-dppm)] (1; dppm = Ph₂PCH₂PPh₂) with nitric oxide, the latter dimerizes and yields the unusual trans-hyponitrite complex [Ru₂(CO)₄(μ-H)(μ-PBu^t₂)(μ-dppm)(μ-η²-ONNO)] (2). The molecular structure of 2 has been determined by X-ray diffraction and is discussed together with the results of DFT calculations. The compound stands out by having only one of the two hyponitrite NO units bonded to Ru. The second one is not connected to Ru but in the solid state exhibits a weak intramolecular bond to the carbon atom of a neighboring carbonyl group.