CLUSTER SYNTHESIS .32. HYDROGEN-RICH METAL CLUSTER COMPLEXES FROM THE REACTION OF PT2OS4(CO)18 WITH HYDROGEN - SYNTHESIS AND MOLECULAR-STRUCTURES OF PTOS5(CO)16(MU-H)6, PT2OS5(CO)17(MU-H)6, PTOS6(CO)18(MU-H)8, AND PT2OS7(CO)23(MU-H)8

From the reaction of Pt2Os4(CO)18 with hydrogen at 25-degrees-C/100 atm, four new hydrogen-rich platinum osmium carbonyl cluster complexes were obtained. They were identified as Pt2Os5(CO)17(mu-H)6 (1), Pt2Os5(CO)17(mu-H)6 (2), Pt2Os7(CO)23(mu-H)8 (3), and PtOs6(CO)18(mu-H)8 (4). All four compounds were characterized by IR, H-1 NMR, and single-crystal X-ray diffraction analyses. The structures of all of the clusters are based on vertex-shared condensed polyhedra using platinum atoms at the vertex-sharing sites. Compound 1 consists of a PtOs3 tetrahedron fused to a PtOs2 triangle. Compound 2 consists of a PtOs3 tetrahedron fused to a OPt2Os2 tetrahedron. compound 3 consists of a PtOs3 tetrahedron fused to a Pt2Os tetrahedron and a PtOs2 triangle sharing the second platinum atom of the Pt2Os2 cluster. Compound 4 consists of two PtOs3 tetrahedra sharing the one platinum atom. Compounds 1 and 2 contain six bridging hydride ligands. The positions of all of the hydride ligands were determined by a combination of H-1 NMR spectroscopy and crystallography. Compounds 3 and 4 both contain eight bridging hydride ligands. The positions of all eight hydride ligands in both compounds were determined by a combination of H-1 NMR spectroscopy and crystallography. Compounds 1-3 are electron deficient by the amount of two electrons. These three complexes are readily degraded by CO (25-degrees-C/1 atm) to yield the products PtOs2(CO)10, H2Os2(CO)4, H2Os(CO)4, and H2. Compound 4 is electronically saturated and does not react with CO at 25-degrees-C/1 atm. Crystal data: for 1, space group P2(1/n), a = 11.810 (4) angstrom, b = 15.656 (4) angstrom, c = 16.286 (6) angstrom, beta = 109.15 (3)-degrees, Z = 4, 2422 reflections, R = 0.032; for 2, space group P2(1)/n, a = 9.603 (3) angstrom, b = 16.246 (7) angstrom, c = 19.272 (7) angstrom, beta = 91.49 (3)-degrees, Z = 4, 2751 reflections, R = 0.042; for 3, space group P2(1)/n, a = 9.616 (1) angstrom, b = 24.411 (9) angstrom, c = 17.065 (4) angstrom, beta = 92.82 (2)-degrees, Z = 4, 3097 reflections, R = 0.029; for 4 space group P1BAR, a = 10.232 (1) angstrom, b = 16.662 (4) angstrom, c = 10.252 (2) angstrom, alpha = 91.04 (2)-degrees, beta = 113.38 (1)-degrees, gamma = 101.37 (2)degrees, Z = 2,2760 reflections, R = 0.029.