Inorganic Chemistry, Vol.35, No.8, 2184-2188, 1996
Application of Dicyanohexasulfane for the Synthesis of Cyclo-Nonasulfur - Crystal and Molecular-Structures of S-6(CN)(2) and of Alpha-S-9
A novel synthesis for dichlorotetrasulfane is reported. Careful chlorination of cyclo-hexasulfur yields S4Cl2 (besides S2Cl2), 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 nb-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 H2S2 and in alpha-S-8.
Keywords:SULFUR-COMPOUNDS;LIQUID-CHROMATOGRAPHY;VIBRATIONAL-SPECTRA;ELEMENTAL SULFUR;S7;CLUSTERS;MELTS;RINGS;S-13;HPLC