Tris(N,N-dialkyldithiocarbamato-S,S')thiotungsten(VI) Complexes and the X-Ray Crystal Structure of [WS(S₂CNEt₂)₃]BF₄

Abstract

The orange, diamagnetic compounds [WS(S₂CNR₂)₃]X(R = Me, X- = BF₄-, BPh₄-;R = Et, X- =BF₄-) were prepared by reacting WSCl₄ and Me₃SiS₂CNR₂ in dichloromethane, followed by metathesis with NaX in methanol. The compounds were characterized by elemental analysis, infrared and variable-temperature ¹H n.m.r. spectroscopy and X-ray crystallography. Crystals of [WS(S₂CNEt₂)₃] BF₄ were monoclinic, space group P2₁/a with a 12.293(1), b 17.229(5), c 14.257(2) Ǻ,β 113.69(1)°, V 2765(2) Ǻ³ and D_c = 1.796 g cm^-3 for Z = 4. The structure was solved by the Patterson method and refined by a full-matrix least-squares procedure, 3961data being used, to a conventional R value of 0.039 ( Rw = 0.040). The seven-coordinate cation possesses a pentagonal-bipyramidal geometry; the terminal thio ligand [W=S 2.127(2)Ǻ] occupies an axial position, a unique dithiocarbamate ligand spans the other axial position and an equatorial position while the two other dithiocarbamate ligands occupy the four remaining equatorial sites.