Crystal structures of tris(NN-diethyldithiocarbamato)oxo-niobium(V) and -vanadium(V)

Abstract

The crystal and molecular structures of the isomorphous and isostructural title compounds [MO(CS₂·NEt₂)₃][(I), M = Nb; (II), M = V] have been determined by single crystal X-ray diffraction, the structures being solved by heavy-atom methods and refined by least-squares methods to R 0·096 [(I) 1680 visually estimated reflections] and 0·103 [(II) 671 diffractometer reflections]. Both are monoclinic, space group P2₁/a, Z= 4; (I): a= 17·28(1), b= 13·305(5), c= 10·774(5)Å; β= 90·09(6)°; (II): a= 17·27(1), b= 13·22(1), c= 10·72(1)Å, β= 90·5(1)°.

In each structure the seven-co-ordinate metal atom is surrounded by an oxygen atom [NbO, 1·74(1), VO, 1·65(2)Å] and three bidentate dithiochelates, two lying in the equatorial plane of a distorted pentagonal bipyramid. The five equatorial distances are almost equal (Nb–S 2·547–2·596, V–S 2·46–2·50 Å) while that opposite to the oxygen is longer (Nb–S 2·753, V–S 2·63 Å). All 0M–S angles are greater than 90°.