PREPARATION OF [OS3(CO)11]2- AND ITS REACTIONS WITH OS3(CO)12 - STRUCTURES OF [ET4N][HOS3(CO)11] AND H2OS4(CO)13

The dianion [OS3(CO)11]2- has been prepared by stoichiometric reductio n of OS3(CO)12 with potassium-benzophenone ketyl. Infrared and C-13 NM R spectra (-120-degrees-C) of [OS3(CO)11]2- reveal the presence of a b ridging carbonyl. Monoprotonation of [OS3(CO)11]2- with HCl gives [HOs 3(CO)11]- in high yield. Reactions of [Os3(CO)11]2- with Os3(CO)12 in 3:1 and 1:1 molar ratios followed by protonation steps give mixtures o f clusters: H2OS4(CO)13, H4OS4(CO)12, H2OS3(CO)10, H2OS5(CO)16, and H2 OS7(CO)20. The structure of [Et4N][HOS3(CO)11] was determined from a s ingle crystal X-ray analysis. The anion structure consists of an OS3 t riangle. One Os atom is bound to four terminal carbonyls, while the ot her two osmiums are each bound to three terminal carbonyls and are bri dged by a CO unit and apparently the H atom. Crystal data for [Et4N][H OS3(CO)11]: space group P2(1)/c, a = 12.439(2) angstrom, b = 11.819(9) angstrom, c = 17.629(4) angstrom, beta = 97.34(1)-degrees, V = 2570.4 angstrom3, Z = 4, mol wt = 1009.6, rho(calcd) = 2.61 g cm-3, mu = 148 .69 cm-1 for Mo Kalpha radiation. R(f) = 0.041, R(wf) = 0.063 for 3558 independent reflections with I greater-than-or-equal-to 3sigma(I). H2 OS4(CO)13 was prepared by the reaction of K2[OS3(CO)11] with Os(CO)5, generated in situ by the reduction of a CO2 with M2[Os(CO)4] (M = Na o r K), followed by protonation. The structure of H2OS4(CO)13 was determ ined from a single crystal X-ray analysis. Its molecular structure is similar to that of H2RU4(CO)13. It consists of a tetrahedral core of O s atoms. There are two semi-bridging carbonyls and two terminal carbon yls bound to the apical Os atom while the three basal Os atoms are eac h bound to two terminal carbonyls. These basal Os atoms are bridged by two single mu-H atoms. Crystal data for H2Os4(CO)13: space group P1BA R, a = 9.129(4) angstrom, b = 26.551(6) angstrom, c = 9.025(5), alpha = 91.95(4)-degrees, beta = 112.27(4)-degrees, gamma = 81.76(3), V= 200 3.1 angstrom3, Z = 4, mol wt = 1126.8, rho(calcd) = 3.74 g cm- 3, mu = 53.98 cm-1 for Mo Kalpha radiation. R(f) = 0.044, R(wf) = 0.062 based upon 7077 independent reflections with I greater-than-or-equal-to 3si gma(I).