Structures,Energies, and Fundamental Vibrations of the Sulfonium Ions H3Sn+ (n = 1–4) |
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Authors: | André H. Otto,Ralf Steudel |
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Abstract: | Using ab initio MO calculations at the MP2/6‐311G(2df,2pd) level of theory the most stable structures of the following seven ions were determined: H3S+ (C3v), H2S–SH+ (Cs), H2S–S–SH+ (C1), HS–S(H)–SH+ (C1), H2S–S–S–SH+ (C1), HS–S(H)–S–SH+ (C1) and S(SH)3+ (C3). In the case of the isomeric H3S3+ cations the species protonated at the terminal sulfur atom is most stable while in the case of the H3S4+ ions the protonation at the β sulfur atom is energetically preferred. However, the energy differences between isomeric cations are rather small. At the same level of theory the wavenumbers of the harmonic fundamental vibrations were calculated and compared to the available experimental data leading to a support for the existing assignments in certain cases but in some cases to revisions. The reaction enthalpies and Gibbs free energies of the proton transfer reactions H2Sn + H2Sn+1 → H3Sn+ + HSn+1– were calculated by the G2 method. For n = 1–3 the enthalpies are found in the range 639–731 kJ mol–1. |
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Keywords: | Sulfur Structures Fundamental Vibrations Thermodynamics ab initio MO calculations |
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