Hydrido- and halogeno-carbonyl complexes

Osmium(n).—Group VII Donors. Hydrido- and halogeno-carbonyl complexes. Carbonylation of [OsHX(CO)(PCy3)2] has produced the novel dicarbonyl hydride [OsHX(CO)2(PCy3)2] (X = Cl or Br Cy = tricyclohexyl).17 I.r. and n.m.r. data indicate the geometry (17). Addition of other ligands to the five-co-ordinate 

Structures (18a) or (18b) were suggested for this species. On the other hand, reaction in the solid state yielded both (18) and another product [OsHCl(CS2)(CO)(PCy3)2], containing terminally S-bonded CS2 [v(C—S) = 1510 cm-1]. 

The related dihydrides [OsH2(CO)(NO)L2]PF6 (L = PPh3, or PCy3) have been synthesized via reaction (17).96 Their XH n.m.r. spectra show them to be stereo- 

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