Vapor-Phase Raman Spectra, Theoretical Calculations, and the Vibrational and Structural Properties of cis- and trans-Stilbene

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• 作者：Toru Egawa ; Kiyoaki Shinashi ; Toyotoshi Ueda ; Esther J. Ocola ; Whe-Yi Chiang ; Jaan Laane
• 刊名：Journal of Physical Chemistry A
• 出版年：2014
• 出版时间：February 13, 2014
• 年：2014
• 卷：118
• 期：6
• 页码：1103-1112
• 全文大小：422K
• ISSN：1520-5215

文摘

The vapor-phase Raman spectra of cis- and trans-stilbene have been collected at high temperatures and assigned. The low-frequency skeletal modes were of special interest. The molecular structures and vibrational frequencies of both molecules have also been obtained using MP2/cc-pVTZ and B3LYP/cc-pVTZ calculations, respectively. The two-dimensional potential map for the internal rotations around the two C_phenyl鈥揅(鈺怌) bonds of cis-stilbene was generated by using a series of B3LYP/cc-pVTZ calculations. It was confirmed that the molecule has only one conformer with C₂ symmetry. The energy level calculation with a two-dimensional Hamiltonian was carried out, and the probability distribution for each level was obtained. The calculation revealed that the 鈥済earing鈥?internal rotation in which the two phenyl rings rotate with opposite directions has a vibrational frequency of 26 cm^鈥?, whereas that of the 鈥渁ntigearing鈥?internal rotation in which the phenyl rings rotate with the same direction is about 52 cm^鈥?. In the low vibrational energy region the probability distribution for the gearing internal rotation is similar to that of a one-dimensional harmonic oscillator, and in the higher region the motion behaves like that of a free rotor.