Variability of niobiumsulfur bond lengths: The molecular structures of sulfido-tris(N,N-diethyldithiocarbamato)niobium(V)

Abstract

In a further examination of the multiply bonded NbS group, the structure of NbS(S 2CNEt 2) 3 has been determined. The compound crystallizes in triclinic space group P1 with a = 9.870(1), b = 15.743(2), c = 16.804(3) Å, α = 101.69(1)°, β = 93.51(1)°, γ = 91.12(1)°, and Z = 4. With use of 6709 unique data (F O2 > 3σ(F O2)) the structure was refined to R(R w) = 3.1(3.5%). The crystal contains two inequivalent molecules with distorted pentagonal bipyramidal coordination in which a sulfide atom occupies an axial position. The molecules are differentiated by ethyl group orientations and significantly different NbS bond lengths of 2.122(1) and 2.168(1) Å. Full structural details are reported. The results fall within the ca. 2.09-2.20 Å interval established with other molecules and emphasize the variability in bond length of the NbS group. Stretching frequencies and bond lengths show a rough inverse dependence. For square pyramidal [NbSCl 4] , with a relatively high NbS bond order, v NbS = 552 cm is associated with a bond length of 2.085(5) Å and an overlap population of 0.64. © 1985.