Molecular structure and barriers to internal rotation of alpha-naphthalenesulfonyl chloride: a study by gas-phase electron diffraction and quantum chemical calculations

作者：Giricheva Nina I; Girichev Georgiy V^*; Dakkouri Marwan; Ivanov Sergey N; Petrov Vjacheslav M; Petrova Valentina N

来源：Structural Chemistry, 2013, 24(3): 819-826.

DOI：10.1007/s11224-013-0265-6

• alpha-Naphthalenesulfonyl chloride
• Geometric structure
• Conformational properties
• Internal rotation, enantiomers, gas electron diffraction
• Mass spectrometry
• Quantum chemical calculations

alpha-Naphthalenesulfonyl chloride, alpha-NaphSC, was studied by gas-phase electron diffraction (GED) and quantum chemical calculations (HF/6-311 + G**, HF/aug-cc-pVDZ, B3LYP/cc-pVDZ, B3LYP/cc-pVTZ, B3LYP/aug-cc-pVDZ, B3LYP/aug-cc-pVTZ, MP2/cc-pVDZ, and MP2/cc-pVTZ). The calculations predict the existence of two conformers with C (1) (I) and C (s) (II) symmetries. The most stable conformer I has an enantiomer. The experimental data of alpha-NaphSC obtained at 370(5) K could be best fitted by a C (1) symmetry model indicating that only this form exists in the gas-phase. In this model the C-alpha-S-Cl plane deviates from the perpendicular orientation relative to the plane of the naphthalene skeleton. Under the applied experimental conditions, the mole fraction of a second less stable conformer II of alpha-NaphSC predicted by calculations is no more than 1 %. The following geometrical parameters of conformer I were obtained from the experiment ( and A degrees; uncertainties are in parentheses): r (h1)(C-H) = 1.082(6), r (h1)(C-C)(cp) = 1.407(3), r (h1)(C-S) = 1.764(5), r (h1)(S-O)(av) = 1.425(3), r (h1)(S-Cl) = 2.051(5), a C-C-alpha-C = 122.5(1), a C-alpha-S-Cl = 101.5(10); C9-C1-S-Cl = 71.4(21). The calculated barriers to internal rotation of the sulfonyl chloride group exceed considerably the thermal energy values corresponding to the temperatures of the GED experiments. Natural bond orbitals analysis of the electron density distribution was carried out to explain the peculiarities of the molecular structure of the studied compound and the deviation from the structures of beta-NaphSHal molecules and their benzene analogs.

• 出版日期2013-6