Oberhalb = 700 K unterliegt c-TiS2 einer Phasenumwandlung zu hexagonalem TiS2 rnit den Gitterkonstanten a = 339.2 und c= 569.1 pm. Sowohl die Richtung der Symmetrieanderung als auch die Verringerung des Gittervolumens (3%) lassen erwarten, dab c-TiS2 metastabil ist. Diffe-. Mitteilung. Diese Arbeit wurde von der Deutschen Forschungsgemeinschaft und dem Fonds der Chemischen Industrie unterstiitzt. -89. Mitteilung: R Steudel in A. Miiller. B. Krebs: Sulphur-Its Significance for Chemistry. for the Geo-. Bio-and Cosmosphere and Technology, Elsevier, Amsterdam 1984. S. 3. 58 Q YCH Verlagsgesellschafi mbH. 0-6940 Weinheim. 1985

poldahafen 2, by quoting the depository number CSD 5 1 119, the names of the authors, and the journal citation. 161 Magnetic measurements: The molar susceptibilities of 1 and 2 were measured on powdered samples in the temperature region 93-293 K Because of its unique thermal behavior, liquid sulfur has been the subject of numerous physicochemical and theoretical investigations. As a rule, it is assumed that, below the polymerization temperature (159"C), the melt essentially consists of S, molecules. However, we have already previously shown by means of vibrational spectra"] that rings other than S, (mainly S,, S6, and S, with n > 8) are present at all temperatures in liquid sulfur, and that these-in comparison with S8-are considerably more reactive species and strongly influence the properties of the melt[21.The separation of sulfur homocycles by means of highpressure liquid chromatography (HPLC)[31 now enables a much more accurate quantitative analysis. Using this technique, we have now found that, after establishment of the equilibrium at constant temperature (23 samples, 13 temperatures) and then quenched in liquid nitrogen, accurately weighed at 20 "C (4.1-7.2g), and immediately extracted quantitatively with ca. 200 mL CS2[41. After filtration and dilution to a prescribed volume, the solution was analyzed quantitatively by HPLC. The insoluble residue (polymeric sulfur, S,) was washed with CS,, dried, and weighed.In the chroma tog ram^'^^, the areas A of 18 S, ring-molecules (n = 6-23) could be measured by electronic integration. For the calibration, at least ten solutions of different concentration c of each of the pure compounds were measured in the case of S6, S,, s8, Sl0, S12, and SZ0. The calibration curve was linear (c = aA) with a correlation coefficient better than 0.9999 over the range 5-500 bg S/mL CS2. Since the slope a is proportional to the number of S atoms in the molecule (except in the case of S7), the calibrations could be calculated for the remaining molecules.Representative analytical values at 13 different temperatures are listed in Table 1. As expected[61, the concentrations of the S, rings ( n f 8 ) pass through a maximum at 159°C: besides 3% S,, only 83.4% S, is present. The missing "rest" of the 100% assay is ascribed to soluble s,, molecules (n > 23) and analytical errors (maximally 3"/0). Molecules with n < 6 were not detectable.After S8 and S,, the most frequently occurring molecules in the melt are S6, S9, and Si2. The relevant reaction enthalpies AH(1) of Equation (1) can be calculated from the temperature-dependence of the concentrations of the molecules listed in Table 1. From the linear regressions in the temperature range 116-159 "C the values shown in Table 2 are obtained.Assuming an equally strong intermolecular interaction (per atom) for all molecules in the melt (zero enthalpy of mixing), the mean bond energies (m.B.E.) in the sulfur rings shown in Figure 1 can be calculated from the AH( I)

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AbstractCyclooctasulfur, S8, dissolved in CS2 reacts at 130-155 °C in sealed ampoules to give S6 and S7 whose concentrations have been determined by HPLC. The half-time of the reaction is independent of the initial S8 concentration and decreases from 232 min at 130 °C to 64 min at 150 °C. After long reaction times equilibrium concentrations are observed which are in agreement with the law of mass action. From the temperature dependence of the equilibrium constants the following reaction enthalpies (at 130-155 °C) have been calculated: 3/4S8⇌S6 ⊿H°=24kJ/mol7/8S8⇌S7 ⊿H°=21kJ/mol

Titanocene pentasulfide reacts with sulfuryl chloride under suitable conditions to give a mixture of mainly S10, S15, and S20 which can be separated by repeated crystallization and precipitation. Pure S15 is obtained as a lemon-yellow powder at low temperatures which transforms to a sticky mass at 20 °C. Solutions of S15 in CS2 are stable at 20 °C for months. Pure S15 does not decompose at 20 °C within a few hours. Raman spectra of S15 show stretching vibrations at 409-480 cm-1 and bending and torsional modes at < 270 cm-1.

Wie durch Hochdruck‐flüssigkeitschromatographische Analyse gezeigt wird, enthalten stöchiometrische Mischungen von [Ti(cp)3S5] und 803C], in CS3 Sm, 8,5, S30 und S35 in abnehmender Konzentration.

Die Einführung der Datenbanktechnik kann die Verarbeitung von Chromatographiedaten wirkungsvoll unterstützen. In diesem Beitrag wird eine Chromatographie‐Software, in die ein Datenbanksystem integriert ist, aus der Sicht von Waters vorgestellt.