Coordination polyhedra OsXn (X = F, Cl, Br, I) in crystal structures

The Voronoi-Dirichlet polyhedra (VDP) and the method of intersecting sphere s were used to perform crystal-chemical analysis of compounds containing co mplexes [OsaXb](z-) (X = F, Cl, Br, I). Atoms of Os(V) at X = F and Cl, of Os(IV) at X = CI, Br, and of Os(III) at X = Br were found to exhibit a coor dination number of 6 with respect to the halogen atoms and to form OsX6 oct ahedra. The coordination polyhedra of Os(III) for X = CI, I are square pyra mids OsX4. Each Os(III) atom forms one Os-Os bond; as a consequence, the Os Br6 octahedra share a face in forming Os2Br93- complexes, while the OsX4 py ramids (X = Cl, I) dimerize to produce [X4Os-OsX4](2-) ions. The influence of the valence state of the Os atoms and of the nature of the halogen atoms on the composition and structure of the complexes formed and some characte ristics of the coordination sphere of Os were considered.