Two isomers of Ru5(C)(CO)14(O2CC6H5)(μ-H): Ru5(C)(CO)14(η2-O2CC6H5)(μ-H), 2 and Ru5(C)(CO)14(μ-O2CC6H5)(μ-H), 3 were obtained from the reaction of Ru5(C)(CO)15 with benzoic acid (PhCO2H). Both compounds were characterized structurally by X-ray diffraction analysis. Compound 2 contains an opened pentaruthenium cluster with a chelating benzoate ligand on the ruthenium atom that was opened. Compound 3 contains an opened pentaruthenium cluster with a benzoate ligand on that bridges a pair of ruthenium atoms which are not mutually bonded. Compound 2 can be converted partially to 3 and 3 partially back to 2 and they form a 1.54/1.0 ratio (3/2) at equilibrium in solution at 95 °C.