Inorg. Chem., 35 (8), 2184 -2188, 1996. ic951225r

Copyright © 1996 American Chemical Society

Application of Dicyanohexasulfane for the Synthesis of cyclo-Nonasulfur. Crystal and Molecular Structures of S6(CN)2 and of -S91

Ralf Steudel,* Klaus Bergemann, Jürgen Buschmann, and Peter Luger

Institut für Anorganische und Analytische Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany, and Institut für Kristallographie, Freie Universität Berlin, Takustrasse 6, D-14195 Berlin, Germany

Received September 22, 1995

Abstract:

A novel synthesis for dichlorotetrasulfane is reported. Careful chlorination of cyclo-hexasulfur yields S4Cl2 (besides S2Cl2), which is used to prepare S6(CN)2 by reaction with Hg(SCN)2. An X-ray diffraction analysis of S6(CN)2 shows nonhelical chainlike molecules with the following molecular parameters: SS bond lengths 203.4-207.4 pm, SSS valence angles 104.95-105.96, SS torsion angles 81.2-94.5 (motif: + + - - +). The chain-terminating SCN groups exhibit a parallel orientation within the molecules and are antiparallel in neighboring molecules. S6(CN)2 reacts with titanocene pentasulfide to give S9 and titanocene diisothiocyanate. -S9 was obtained as single crystals, the structure of which was determined by X-ray diffraction. The two independent molecules occupy sites of C1 symmetry, but the molecular symmetry is approximately C2, in agreement with predictions by density functional and ab-initio MO calculations. Molecular parameters: bond lengths 203.2-206.9 pm, valence angles 103.7-109.7, torsion angles 59.7-115.6 (motif: + + - - + + - + -). The average SS bond lengths in S6(CN)2 and -S9 agree with the single-bond value of 205 pm as observed in H2S2 and in -S8.