Pincer ligand coordination at Co3 and Ru6 clusters: Syntheses, reactivity studies, and X-ray diffraction structures of [PhCCo3(CO)8]2(dppx) and [Ru6(μ6-C)(CO)16]2(dppx)

The reaction of the pincer diphosphine ligand 4,6-bis(diphenylphosphinomethyl)-m-xylene (dppx) with the metal cluster compounds PhCCo3(CO)9 and Ru6(μ6-C)(CO)17 has been explored. Both clusters react with dppx to afford the simple substitution products [PhCCo3(CO)8]2(dppx) and [Ru6(μ6-C)(CO)16]2(dppx), where two cluster units are tethered by the pincer ligand. The molecular structures of the title products and the 2:1 cluster-pincer ligand stoichiometry have been established by X-ray crystallography. The stability of [PhCCo3(CO)8]2(dppx) and [Ru6(μ6-C)(CO)16]2(dppx) has been investigated under gentle thermolysis conditions (ca. 55–65°C). Both dppx-substituted clusters are unstable with [PhCCo3(CO)8]2(dppx) decomposing and [Ru6(μ6-C)(CO)16]2(dppx) transforming into the diphosphine-bridged cluster Ru6(μ6-C)(CO)15(μ-dppx) as the major observable product. The identity of the latter cluster has been ascertained by IR and NMR spectroscopies and mass spectrometry.