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Molecular structure and conformations of 1-phenyl-1-silacyclohexane from gas-phase electron diffraction and quantum chemical calculations

Research paper by Bagrat A. Shainyan, Svetlana V. Kirpichenko, Dmitriy Yu. Osadchiy, Sergey A. Shlykov

Indexed on: 27 May '14Published on: 27 May '14Published in: Structural Chemistry



Abstract

Molecular structure and conformational behavior of the title compound 1 were studied experimentally by gas-phase electron diffraction (GED–MS) and theoretically (DFT and MP2). Only two of four possible conformers of 1 differing by axial or equatorial location of the phenyl group and the angle of rotation about the Si–CPh bond contribute to the equilibrium; these are the 1-eq conformer with the phenyl ring plane perpendicular to the averaged silacyclohexane plane and the 1-ax conformer with the phenyl ring and Si–C6 bond lying approximately in one plane. The ratio 1-eq:1-ax is 62 (10):38 (10), which is only slightly different from 78:22 in solution. The presence of up to 10 % of 1-ax_orth conformer cannot be excluded either. The corresponding ΔG values are 0.29 and 0.25 kcal mol−1. The GED molecular structure of 1 is nicely reproduced by DFT and MP2 calculations.

Graphical abstract 10.1007/s11224-014-0444-0.gif

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