Bhagyasree J B, Varghese Hema Tresa, Panicker C Yohannan, Van Alsenoy Christian, Al-Saadi Abdulaziz A, Dolezal Martin, Samuel Jadu
Department of Chemistry, Mar Ivanios College, Nalanchira, Trivandrum, Kerala, India.
Department of Physics, Fatima Mata National College, Kollam, Kerala, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2015 Feb 25;137:193-206. doi: 10.1016/j.saa.2014.08.104. Epub 2014 Sep 3.
The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 5-tert-Butyl-6-chloro-N-[(4-(trifluoromethyl)phenyl]pyrazine-2-carboxamide have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of normal modes of vibrations was done using GAR2PED program. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. From the NBO analysis it is evident that the increased electron density at the nitrogen, carbon atoms leads to the elongation of respective bond length and a lowering of the corresponding stretching wave number. The calculated geometrical parameters are in agreement with that of similar derivatives. The calculated first hyperpolarizability is high and the calculated data suggest an extended π-electron delocalization over the pyrazine ring and carboxamide moiety which is responsible for the nonlinearity of the molecule.
使用Gaussian09软件包，通过实验和理论方法研究了5-叔丁基-6-氯-N-[(4-(三氟甲基)苯基]吡嗪-2-甲酰胺的优化分子结构、振动频率及其相应的振动归属。使用GAR2PED程序进行了正常振动模式的势能分布计算。利用HOMO和LUMO分析来确定分子内的电荷转移。使用NBO分析研究了由超共轭相互作用和电荷离域引起的分子稳定性。从NBO分析中可以明显看出，氮、碳原子处电子密度的增加导致相应键长的伸长和相应伸缩波数的降低。计算得到的几何参数与类似衍生物的参数一致。计算得到的第一超极化率较高，计算数据表明π电子在吡嗪环和甲酰胺部分上有扩展的离域，这是分子非线性的原因。
