Structure analysis of twinned crystals of tris(N,N-di-n-butyldiselenocarbamato)nickel(IV) bromide

Abstract

The crystal structure of tris(N,N-di-n-butyldiselenocarbamato)nickel(IV) bromide, Ni(Se₂CN-(C₄H₉)₂)₃Br, has been determined by three-dimensional X-ray methods. The Laue symmetry is 6/mmm, but the structure could be solved only in space groupP¯31c. The crystals were, therefore, regarded as being microtwinned on (001). The unit cell dimensions area =b = 14·69(3) andc = 10·91(3) Å. From integrated Weissenberg photographs, 307 non-zero symmetry-independent reflexions were measured photometrically. The structural parameters were refined by least-squares methods to a conventionalR factor of 0·10. The quadrivalent nickel atom is octahedrally coordinated by six selenium atoms. The Ni-Se distance is 2·391(5) Å; the Se-Se distance within one diselenocarbamate ligand is 3·00(1) Å; Se-Se distances between different ligands are 3·51(1), 3·52(1) and 3·55(1) Å.