Reactivity of [Ru4(μ-H)4(CO)12] with bidentate ligands containing at least one N-heterocyclic carbene moiety

The tetraruthenium carbonyl cluster complexes [Ru4(μ-H)4(κ2-Ln)(CO)10], which contain a ditopic ligand (Ln) in which an N-heterocyclic carbene moiety is combined with a thioether (L1), a phosphine (L2 and L3), an NHC (L4), or a pyridine (L5 and L6) fragment, have been prepared by treating [Ru4(μ-H)4(CO)12] with the corresponding ligand. In these compounds, the ditopic ligand chelates a ruthenium atom that is also attached to three hydrides. In the reactions involving L1, L2 and L3, an ionic species, identified as [HLn]+ [Ru4(μ-H)3(CO)12]−, has been recognized as a reaction intermediate.