Cyclic polysilanes : XIX. A temperature study of redistribution equilibria between permethylcyclopolysilanes |
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Authors: | Lawrence F Brough Robert West |
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Institution: | Department of Chemistry, University of Wisconsin, Madison, WI 53706 U.S.A. |
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Abstract: | Equilibria among the cyclic compounds (Me2Si)n where n = 5, 6 and 7 have been studied between 30–58°C. Thermodynamic values for the redistribution reactions between pairs of compounds are, for n = 5 → 6, ΔH = ?18 kcal/mole, ΔS = ?20 cal/deg. mole; for n = 7 → 6, ΔH ?3, ΔS +33; for n = 7 → 5, ΔH +18, ΔS + 51. The enthalpies indicate that the stabilities of the rings increase in the order (Me2Si)5 < (Me2Si)7 < (Me2Si)6. The differences are smaller than corresponding differences among the cycloalkanes, probably because the silicon compounds are less affected by steric repulsions and angle strain. |
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