STRUCTURALLY UNUSUAL TRIHYDRIDO-TRIOSMIUN CLUSTERS

The reactions of (mu-H)(mu(3)-eta(2)-C=NCH2CH2CH2)Os-3(CO)(9) (1) with H-2, H2S, and C2H5SH are reported. In the case of H-2 a trihydrido cl uster in which all metal-metal bonds are retained is formed, K(mu-H)(2 )(mu(3)-eta(2)-C=NCH2CH2CH2)Os-3(CO)(8) (2), along with minor byproduc ts. The hydrides in 2 are rigid on the NMR time scale, but reaction wi th PPh(3) yields the related mu-eta(2)-C=dbCLNCH(2)CH(2)CH(2))Os-3(CO) (8)PPh(3) (5), in which the hydrides exhibit dynamic behavior on the N MR time scale which has been examined in detail. The reaction of 1 wit h H2S yields a set of isomeric trihydride clusters in which two of the three metal-metal bonds have been cleaved, (mu-H)(mu(3)-S)(mu-eta(2)- C=NCH2CH2CH2)Os-3(CO)(9) (7), while reaction with C2H5SH yields the di hydride H(mu-H)(mu-S)(mu-eta(2)-C=NCH2CH2CH2)Os-3(CO)(9) help elucidat e the pathway of formation of 7. Solid-structures of 2, 5, and 7a are reported. Compound 2 crystallizes in the monoclinic space group P2(1)/ with unit cell parameters a = 7.113(2) Angstrom, b = 16.227(2) Angstro m, c = 15.171(3) Angstrom, beta = 91.33(2)degrees, V = 1751(1) Angstro m(3), and Z = 4. Least-squares refinement of 1837 observed reflections gave a final agreement factor ofR = 0.054 (R(w) = 0.061). Compound 5 crystallizes in space group Pbca with unit cell parameters a 15.230(3) Angstrom, b = 16.871(2) Angstrom, c = 24.947(5) Angstrom, V = 6410(3) Angstrom(3), and Z = 8. Least-squares refinement of 3943 observed ref lections gave a final agreement factor ofR = 0.050 (R(w) = 0.053). Com pound 7a crystallizes in the monoclinic space group P2(1)/n with unit cell parameters a Z 10.541(2) Angstrom, b = 15.151(3) Angstrom, c = 12 .281(3) Angstrom, beta = 91.35(2)degrees, V = 1961(1) Angstrom(3), and Z = 4. Least-squares refinement of 2408 observed reflections gave a f inal agreement factor of R = 0.058 (R(w) = 0.067).