S(N,N-DIALKYLDITHIOCARBAMATO-S,S')THIOTUNGSTEN(VI) COMPLEXES AND THE X-RAY CRYSTAL-STRUCTURE OF [WS(S(2)CNET(2))(3)]BF4

The orange, diamagnetic compounds [WS(S(2)CNR(2))(3)] X (R = Me, X(-) = BF4-, BPh(4)(-); R = Et, X(-) = BF4-) were prepared by reacting WSCl 4 and Me(3)SiS(2)CNR(2) in dichloromethane, followed by metathesis wit h NaX in methanol. The compounds were characterized by elemental analy sis, infrared and variable-temperature H-1 n.m.r. spectroscopy and X-r ay crystallography. Crystals of [WS(S(2)CNEt(2))(3)] BF4 were monoclin ic, space group P2(1)/a with a 12.293(1), b 17.229(5), c 14.257(2) Ang strom, beta 113.69(1)degrees, V 2765(2) Angstrom(3) 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, 3961 data being use d, to a conventional R value of 0.039 (R(w) = 0.040). The seven-coordi nate cation possesses a pentagonal-bipyramidal geometry; the terminal thio ligand [W=S 2.127(2) Angstrom] occupies an axial position, a uniq ue dithiocarbamate ligand spans the other axial position and an equato rial position while the two other dithiocarbamate ligands occupy the f our remaining equatorial sites.