{(COD)Ru[RNdouble bond; length as m-dashC(H)–C(H)double bond; length as m-dashC(Ph)]2} (Rdouble bond; length as m-dashMe, Et): The first structurally characterized mononuclear ruthenium complexes with enyl-imino ligands and their relevance in ruthenium ca

The reaction of α,β-unsaturated imines with [(1,5-cyclooctadiene)-bis(2-methylallyl)-ruthenium(II)] leads to the formation of mononuclear ruthenium complexes of the general formula {(COD)Ru[RNdouble bond; length as m-dashC(H)–C(H)double bond; length as m-dashC(Ph)]2}. In these complexes the imine ligands are deprotonated in β-position with respect to the imine double bond and coordinate as an enyl-imino ligand. In the case of R = Me, Et the corresponding compounds have been characterized by X-ray crystallography. The relevance of these complexes with respect to ruthenium catalyzed C–C coupling reactions of the same α,β-unsaturated imines is demonstrated by the structural analysis of another mononuclear ruthenium complex in which two imine ligands are reductively coupled (R = Cy). [(1,5-Cyclooctadiene)-bis(2-methylallyl)-ruthenium(II)] also turns out to be a highly effective precatalyst in the reaction of the respective imines with carbon monoxide and ethylene to produce heterocyclic compounds.