title: Synthesis and Conformational Analysis of 3-Methyl-3-silatetrahydropyran by GED, FTIR, NMR, and Theoretical Calculations: Comparative Analysis of 1-Hetero-3-methyl-3-silacyclohexanes.
abstract: 3-Methyl-3-silatetrahydropyran 1 was synthesized and its molecular structure and conformational behavior was studied by gas-phase electron diffraction (GED), FTIR, low temperature (1)H and (13)C NMR spectroscopy, and by theoretical calculations (DFT, MP2). Two conformers, 1-ax and 1-eq, were located on the potential energy surface. In the gas phase, a slight predominance of the axial conformer was determined, with the ratio 1-ax:1-eq = 54(9):46(9) (from GED) or 53:47 or 61:39 (from IR). In solution, LT NMR spectroscopy at 103 K gives the ratio 1-ax:1-eq = 35:65 (-ΔG°103 = 0.13 kcal/mol). Simulation of solvent effects using the PCM continuum model or by calculation of the corresponding solvent-solute complexes allowed us to rationalize the experimentally observed opposite conformational predominance of the conformers of 3-methyl-3-silatetrahydropyran in the gas phase and in solution. Comparative analysis of the effect of heteroatom in 1-hetero-3-methyl-3-silacyclohexanes on the structure, stereoelectronic interactions, and relative energies of the conformers is done.
authors.affiliation: A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Division of the Russian Academy of Sciences , 1 Favorsky Street, Irkutsk 664033, Russian Federation.
authors.forename: Bagrat A
authors.initials: BA
authors.lastname: Shainyan
authors.affiliation: A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Division of the Russian Academy of Sciences , 1 Favorsky Street, Irkutsk 664033, Russian Federation.
authors.forename: Svetlana V
authors.initials: SV
authors.lastname: Kirpichenko
authors.affiliation: A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Division of the Russian Academy of Sciences , 1 Favorsky Street, Irkutsk 664033, Russian Federation.
authors.forename: Nina N
authors.initials: NN
authors.lastname: Chipanina
authors.affiliation: A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Division of the Russian Academy of Sciences , 1 Favorsky Street, Irkutsk 664033, Russian Federation.
authors.forename: Larisa P
authors.initials: LP
authors.lastname: Oznobikhina
authors.affiliation: Chemisches Institut der Universität Potsdam , Karl-Liebknecht-Strasse 24-25, Potsdam (Golm) D-14476, Germany.
authors.forename: Erich
authors.initials: E
authors.lastname: Kleinpeter
authors.affiliation: Ivanovo State University of Chemistry and Technology , Research Institute for Thermodynamics and Kinetics of Chemical Processes, Sheremetev avenue 7, Ivanovo 153000, Russian Federation.
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Shlykov
authors.affiliation: Ivanovo State University of Chemistry and Technology , Research Institute for Thermodynamics and Kinetics of Chemical Processes, Sheremetev avenue 7, Ivanovo 153000, Russian Federation.
authors.forename: Dmitriy Yu
authors.initials: DY
authors.lastname: Osadchiy