Triangular W3S74+ and W3S44+ complexes

Methods for the synthesis of triangular thiohalogenide complexes of tungsten W3S7X4 (XCl, Br) proceeding from metallic tungsten or WS3 have been developed. Ways have been found for converting these polymeric complexes to triangular W3S7X62− complexes which preserve the architecture of the W3(μ3-S)(μ2-S2)34+ cluster fragment. Heating W3S7X4 in a PPh4X melt or in concentrated acids HX in the presence of Et4NX afforded PPh4+ and Et4N+ salts of W3S7X62− (XCl, Br). The structure of (Ph4P)2W3S7Br6 (III) was established by X-ray diffraction analysis. The crystals of III are orthorhombic, a=18.082(2), b=25.834(3), c=27.370(2) Å, Z=8, Pbca, R (Rw)=0.049 (0.055). The Et4N+ salt of W334S7Br62− has been obtained and a calculation of the normal vibrations has been performed for W3S7Br62−. Interaction of W3S7Br4, with a KNCS melt or an aqueous solution of (NH4)2Sx involves transformation of the cluster fragment W3S74+ to a W3S44+ fragment to produce W3S4(NCS)95− and W3S4(S4)3(NH3)32− complexes. The structure of (NH4)(H)(H2O)3W3S16(NH3)3 (VI) was established by X-ray diffraction analysis. The crystals of VI are trigonal, a=12.508(1), c=10.112(1) Å, Z=2, P31c, R (Rw)=0.029 (0.033).