CLUSTER SYNTHESIS .30. NEW PLATINUM OSMIUM CARBONYL CLUSTER COMPLEXES FROM THE REACTION OF OS3(CO)10(NCME)2 WITH PT(COD)2

Two new platinum-osmium carbonyl cluster complexes, Pt2Os3(CO)10(COD)2 (1) and PtOs3(CO)8(COD)(mu-C8H11)(mu-H) (2), were obtained in yields of 18% and 4%, respectively, from the reaction of Os3(CO)10(NCMe)2 with Pt(COD)2 at 25-degrees-C. Both products were characterized by IR, H-1 NMR, and single-crystal X-ray diffraction analyses. Compound 1 contains a tetrahedral Pt2Os2 cluster with an Os(CO)4 group bridging the Os-Os edge. Compound 2 contains a tetrahedral PtOs3 cluster with a COD ligand activated at one of the olefin C-H bonds bridging an Os-Os edge of the cluster. Compound 1 is formally electron deficient and readily reacts with CO at 25-degrees-C/1 atm to yield a series of two products, Pt2Os3(CO)14 (3) and the known complex PtOs2(CO)10 (4). 3 and 4 were both characterized by single-crystal X-ray diffraction analyses. Compound 3 contains two structurally similar but symmetry-independent molecules in the crystal. Both molecules contain planar clusters of five metal atoms, with a "truncated raft" structure. Compound 4 contains a triangle of one platinum and two osmium atoms. Compound 3 reacts with Os(CO)5 to form the known compound Pt2Os4(CO)18 (5) in 92% yield. Crystal data: for 1, space group Pnma, a = 11.559 (2) angstrom, b = 14.984 (2) angstrom, c = 17.222 (4) angstrom, R = 0.037 for 1891 reflections; for 2, space group P21/c, a = 10.433 (2) angstrom, b = 10.066 (2) angstrom, c = 24.976 (3) angstrom, beta = 92.52 (1)-degrees, R = 0.028 for 2825 reflections; for 3, space group P21/c, a = 14.895 (3) angstrom, b = 12.060 (2) angstrom, c = 25.615 (3) angstrom, beta = 92.87 (1)-degrees, R = 0.040 for 2740 reflections; for 4, space group P1BAR, a = 8.997 (3) angstrom, b = 12.888 (3) angstrom, c = 7.082 (2) angstrom, alpha = 98.52 (2)-degrees, beta = 105.61 (2)-degrees, gamma = 81.51 (2)-degrees, R = 0.034 for 2051 reflections.