title: Application of Dicyanohexasulfane for the Synthesis of cyclo-Nonasulfur. Crystal and Molecular Structures of S(6)(CN)(2) and of alpha-S(9)(1).
abstract: A novel synthesis for dichlorotetrasulfane is reported. Careful chlorination of cyclo-hexasulfur yields S(4)Cl(2) (besides S(2)Cl(2)), which is used to prepare S(6)(CN)(2) by reaction with Hg(SCN)(2). An X-ray diffraction analysis of S(6)(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 degrees, SS torsion angles 81.2-94.5 degrees (motif: + + - - +). The chain-terminating SCN groups exhibit a parallel orientation within the molecules and are antiparallel in neighboring molecules. S(6)(CN)(2) reacts with titanocene pentasulfide to give S(9) and titanocene diisothiocyanate. alpha-S(9) was obtained as single crystals, the structure of which was determined by X-ray diffraction. The two independent molecules occupy sites of C(1) symmetry, but the molecular symmetry is approximately C(2), 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 degrees, torsion angles 59.7-115.6 degrees (motif: + + - - + + - + -). The average SS bond lengths in S(6)(CN)(2) and alpha-S(9) agree with the single-bond value of 205 pm as observed in H(2)S(2) and in alpha-S(8).
authors.affiliation: 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.
authors.forename: Ralf
authors.initials: R
authors.lastname: Steudel
authors.forename: Klaus
authors.initials: K
authors.lastname: Bergemann
authors.forename: Jürgen
authors.initials: J
authors.lastname: Buschmann
authors.forename: Peter
authors.initials: P
authors.lastname: Luger