New high nuclearity platinum-ruthenium carbonyl cluster complexes containing a phenylacetylene ligand: Structures and properties

Reaction of the mixed-metal carbonyl cluster complex Ru-5(CO)(15)(C)[Pt(PBu3t)], 3, with PhC2H yielded the new compound PtRu5(CO)(13)(PBu3t)(/mu(5)-C)(mu(3)-PhC2H), 4, in 41% yield. Two new bimetallic cluster complexes, Pt2Ru5(CO)(13)(PBu3t)(2)(mu(5)-C)(mu(3)-PhC2H), 5, and Pt3Ru5(CO)(13)(PBu3t)(3)(mu(5)-C)(mu(3)-PhC2H), 6, were subsequently obtained in 44% and 40% yield, respectively, from the reaction of 4 with an excess of Pt(PBu3t)(2). All products were characterized crystallographically by single-crystal X-ray diffraction techniques. The structure of 4 consists of a square-pyramidal cluster of five ruthenium atoms with a Pt(PBu3t) group capping one of the Ru-3 triangles. A PhC2H ligand bridges one of the PtRu2 triangles. Compounds 5 and 6 are similar to 4 but have in addition one and two Pt(PBu3t) groups bridging one and two edges of the Ru5 square-pyramidal portion of the cluster. Compound 6 was shown to be dynamically active on the P-31 NMR time scale by a process that involves an interchange of two of its inequivalent Pt(PBu3t) groups.