An Air-Stable Dimeric Ru–S Complex with an NHC as Ancillary Ligand for Cooperative Si–H Bond Activation

The preparation of a coordinatively unsaturated NHC ruthenium complex with a tethered 2,6-dimesitylphenyl thiolate is described. Unlike related mononuclear phosphine complexes, the NHC complex forms an air-stable dimer with bridging sulfur ligands in both the solid state and solution. The dinuclear complex is a precatalyst and activates Si–H bonds upon heat- or donor-assisted dissociation into the catalytically active monomer. Its usefulness is illustrated with representative dehydrogenative Si–X coupling and hydrosilylation reactions.