X-Ray and neutron diffraction study of 1,1,1,2,2,2,3,3,3-nonacarbonyl-1,2;1,3-di-µ-hydrido-µ₃-sulphido-triangulo-triosmium

The title complex [Os3(CO)9H2(S)] crystallises in the monoclinic space group C2/c with a= 20.476(10), b= 13.952(7), c= 12.939(6)Å, β= 123.84(3)°, and Z= 8. Simultaneous refinement of a single parameter set to 2 436 X-ray [(sinθ)/λ > 0.45] and 1 292 neutron data has led to R 0.038 (X-ray) and 0.037 (neutron). The two longer edges of the Os3 isosceles triangle are bridged by hydrides, which lie on the opposite side of the Os3 plane to the triply bridging sulphur atom. Each osmium is also bonded to three terminal carbonyls. The Os–H–Os linkages can be described as 'open' three-centre two-electron bent bonds, with little direct Os–Os interaction. Both hydride bridges are significantly asymmetric, the hydrogen atoms being ca. 0.025 Å closer to the unique osmium. The mean Os–H distance is 1.819 Å, and both Os–H–Os angles are 106.5(2)°.