Structural characterization of a hexameric cobalt-carbonyl-sulfur complex, [Co3(CO)9C](.mu.3-SCS)[Co3(CO)7S], consisting of two tricobalt carbonyl clusters dissymmetrically linked by a bridging SCS group

Abstract

The reaction of Co/sub 2/(CO)/sub 8/ with CS/sub 2/ at room temperature has resulted in the formation of the new hexameric cobalt-carbonyl-sulfur complex (Co/sub 3/(CO)/sub 9/C)(..mu../sub 3/-SCS)(Co/sub 3/(CO)/sub 7/S) containing a four-electron-donor SCS ligand dissymmetrically linked to two tricobalt clusters, as opposed to the structural isomer (Co(CO)/sub 9/C)(..mu../sub 3/-CS/sub 2/)(Co/sub 3/(CO)/sub 7/S), in which the linkage of the CS/sub 2/ group to the identical two tricobalt clusters is symmetric. The structure has been unambiguously characterized by X-ray analysis. The crystals contain four formula species in an orthorhombic cell of symmetry Pnma and of dimensions a = 17.067 (5) A, b = 13.074 (5) A, and c = 13.493 (5) A. Full-matrix least-squares refinement of 32 independent atoms has yielded discrepancy indexes R(F) = 0.056 and R(F/sup 2/) = 0.049 based on 777 reflections with F/sub 0//sup 2/ greater than or equal to sigma(F/sub 0//sup 2/). The disordered-crystal model successfully utilized in the refinement assumes a random distribution of each molecule in one of two orientations related to each other by a crystallographic mirror plane. In the Co/sub 3/(CO)/sub 9/C fragment, which is related to itself by the mirror plane, the Co/sub 3/C unit forms a tetrahedron with an idealized C/submore » 3v/-3m symmetry with its apical carbon being utilized to form a sigma bond with one ligand sulfur atom, while in the Co/sub 3/(CO)/sub 7/S fragment the triangle of basal cobalt atoms takes up an isosceles array due to distortion caused by the formation of cobalt-carbon and cobalt-sulfur bondings. As in other cases of statistically disordered structures, the resulting molecular configuration precludes the accurate determination of molecular parameters, thereby resulting in some anomalous geometries in the molecule. 35 references, 1 figures, 3 tables.« less