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Dynamics of internal rotation in styrene by analysis of high resolution 1H NMR multiplet structure and dynamic FPT DFT calculationsтезисы доклада
- Авторы: Cheshkov D.A., Ganina T.A., Sinitsyn D.O., Chertkov V.A.
- Сборник: EUROMAR-2011 Magnetic Resonance Conference, Frankfurt, 2011, Abstracts
- Тезисы
- Год издания: 2011
- Место издания: The Magnetic Resonance Spectroscopy Division of the Gesellschaft Deutscher Chemiker (GDCh) Frankfurt
- Первая страница: 277
- Последняя страница: 277
- Аннотация: Styrene is the classical system with hindered internal rotation of vinyl group around С1–Сi bond. Previously attempted studies of this dynamics gave inconsistent results (see discussion in [1]). Here we report results based on detailed analysis of 1H NMR spectra and a series of quantum mechanics calculations for dynamic systems vibrating with large amplitude. 1H NMR spectral analysis for styrene dissolved in CDCl3, CD3CN and C6D6 was performed with total lineshape iteration program VALISA [2]. For determitation of relative signs of 1H-1H couplings between aromatic and olefinic protons we calculated spin systems with all possible combinations of these couplings. Simultaneously we performed dynamic FPT DFT (B3LYP/aug-cc-pVTZ) calculations of the couplings. Dynamics of internal rotation was evaluated by numerical solution of vibrational problem. Calculated spin-spin coupling constants were obtained by averaging of corresponding conformational dependencies with vibrational distribution function. Experimental and calculated spin-spin coupling constants are in reasonable agreement to each other. The best-fit potential has a minimum for skewed conformation with dihedral angle 30o. The “plane” and “orthogonal” forms have energies of 0.66 and 2.64 kcal/mol.
- Добавил в систему: Чертков Вячеслав Алексеевич