A bi-butterfly W-Cu-S cluster compound: Synthesis and crystal structure of (n-Bu4N)2[W2Cu4S8(S2CNC4H8)2]

The compound (n-Bu4N)2[W2Cu4S8(S2CNC4H8)2] was obtained by the reaction of Bu4NBr, (NH4)2WS4, NaS2NCC4H8 and CuCl in CH3CN and CH3OH. It crystallizes in the monoclinic space group P21/c with unit cell parameters: a=21.875(5), b=16.843(4), c=17.745(5)A, β = 101.69(6)°, V=6402(6)A3, Z=4, Dc=1.718 g·cm−3. The final R and Rw values converged to 0.055 and 0.060 respectively. The structure consists of two ‘butterfly’ units [WS4Cu2] linked together by two weak Cu—S bonds and two bridging S2CNC4H8 ligands. Infrared spectra gave characteristic absorptions at 495 cm−1 for W=S and 450, 435, 412 cm−1 for W—μ-S.