Synthesis, spectroscopic and x-ray structure characterisation of bis(tetramethylammonium), bis(tetraethylammonium) and bis(tetrapropylammonium) tetrathiotungstates

Abstract

The three new tetraalkylammonium tetrathiotungstates ((Me) 4N)2[WS4] (1), ((Et)4N) 2[WS4] (2) and ((nPr)4N)2[WS 4] (3) were prepared via a direct salt substitution using (NH 4)2[WS4] as starting material. Compound 1 crystallises in the chiral orthorhombic space group P212 121 with a = 8.9433(4), b = 15.5658(9) and c = 37.279(2) Å. Compound 2 crystallises in space group P21/n with lattice parameters a = 16.6695(12), b = 9.3415(6), c = 16.9965(13) Å and β = 117.185(15)°. The third compound 3 crystallises in space group C2/c with the lattice parameters a = 32.440(2), b = 13.8453(6), c = 15.0563(10) Å and β = 109.19(7)°. The structures of all compounds consist of slightly distorted [WS4]2- tetrahedra and tetraalkylammonium cations which are packed in different ways. One interesting observation is that the disorder of parts of the alkyl groups decreases with increasing chain length. The IR and Raman spectra show the vibrations of the [WS 4]2- tetrahedron with a slight shift with increasing alkyl chain length. The most prominent IR-band of the [WS4]2- tetrahedra is broad but not split, indicating that the distortion of the tetrahedra is small. © 2006 Verlag der Zeitschrift für Naturforschung.