Details

Autor(en) / Beteiligte

• Shainyan, B.A
• Kleinpeter, E
• Suslova, E.N

Titel

Conformational Analysis of disiloxane. DFT and Low-Temperature [sup.13]C NMR Spectroscopy Study

Ist Teil von

• Russian journal of general chemistry, 2019-04, Vol.89 (4), p.713

Ort / Verlag

Springer

Erscheinungsjahr

2019

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The DFT and MP2 theoretical conformational analysis of the recently synthesized (1,1'-phenyl-1,1'silacyclohex-1- yl)disiloxane has revealed the energetic preference of the [Ph.sub.ax], [Ph.sub.ax] conformer. The [Ph.sub.ax], [Ph.sub.ax] : [Ph.sub.ax], [Ph.sub.eq] : [Ph.sub.eq], [Ph.sub.eq] conformers ratio has been estimated as of 46.6 : 33.1 : 20.3 from the M062X/6-311G(d, p) free energy simulation, suggesting the possibility of detecting individual conformers experimentally, e.g., by low-temperature [sup.1]H and [sup.13]C NMR spectroscopy. However, only the presence of several conformers has been detected by means of 1H NMR spectroscopy at 113 K; determination of the [DELTA]v (Hz) and [DELTA][G.sup.#] (kcal/mol) parameters for the 6-membered ring interconversion has been impossible due to the signals broadening at low temperature, signal temperature shifts, and extremely low barrier of ring inversion at [T.sub.c] < 113 K. Keywords: siloxanes, silacyclohexanes, conformational analysis, DFT and MP2 simulation, low-temperature NMR spectroscopy DOI: 10.1134/S1070363219040121