A facile and benign synthesis of binuclear ruthenium(I) “sawhorse” complexes

Polymeric dicarbonyldichlororuthenium(II) [Ru(CO)2Cl2]n is reduced by reaction with carboxylate salts (RCO2−Na+) in alcoholic suspension. Dimeric ruthenium(I) “sawhorse” complexes [Ru(RCO2)(CO)2L]2 (R = Me, Et, But, Ph) are formed on the addition of a monodentate ligand, L [L = pyridine (py) or 3-methylpyridine (Mepy)]. Characterisation of [Ru(MeCO2)(CO)2(py)]2, [Ru(MeCO2)(CO)2(Mepy)]2, [Ru(EtCO2)(CO)2(py)]2, [Ru(ButCO2)(CO)2(py)]2 and [Ru(PhCO2)(CO)2(py)]2 by IR and 1H NMR spectroscopy is reported. Structural elucidation by single crystal X-ray diffraction was achieved in each case revealing a dicarboxylate bridged diruthenium(I) complex with cisoid carbonyls and pyridine ligands approximately collinear with the ruthenium–ruthenium bond.