Abant Izzet Baysal University, Department of Physics, Bolu 14280, Turkey.
Spectrochim Acta A Mol Biomol Spectrosc. 2011 Oct 15;81(1):104-10. doi: 10.1016/j.saa.2011.05.056. Epub 2011 May 30.
This study deals with the identification of a title compound, 2,6-dimethyl-4-nitropyridine N-oxide by means of theoretical calculations. The optimized molecular structures, vibrational frequencies, corresponding vibrational assignments, thermodynamic properties and atomic charges of the title compound in the ground state were evaluated using density functional theory (DFT) with the standard B3LYP/6-311G(d,p) method and basis set combination for the first time. Theoretical vibrational spectra were interpreted with the aid of normal coordinate analysis based on scaled density functional force field. The results show that the optimized geometric parameters (bond lengths and bond angles) and vibrational frequencies were observed to be in good agreement with the available experimental results. Based on the results of comparison between experimental results and theoretical data, the chosen calculation level is powerful approach for understanding the molecular structures and vibrational spectra of the 2,6-dimethyl-4-nitropyridine N-oxide. Moreover, we not only simulated frontier molecular orbitals (FMO) and molecular electrostatic potential (MEP) but also determined the transition state and energy band gap. Based on the investigations, the title compound is found to be useful to bond metallically and interact intermolecularly. Infrared intensities and Raman activities were also reported.
本研究通过理论计算对标题化合物 2,6-二甲基-4-硝基吡啶 N-氧化物进行了鉴定。采用密度泛函理论（DFT），首次使用标准 B3LYP/6-311G(d,p)方法和基组组合，对标题化合物在基态下的优化分子结构、振动频率、相应的振动分配、热力学性质和原子电荷进行了评估。理论振动光谱通过基于比例密度泛函力场的正则坐标分析进行了解释。结果表明，优化的几何参数（键长和键角）和振动频率与可用的实验结果吻合良好。基于实验结果与理论数据的比较结果，所选的计算水平是理解 2,6-二甲基-4-硝基吡啶 N-氧化物的分子结构和振动光谱的有力方法。此外，我们不仅模拟了前沿分子轨道（FMO）和分子静电势（MEP），还确定了过渡态和能带隙。基于这些研究，发现标题化合物在金属键合和分子间相互作用方面很有用。还报道了红外强度和拉曼活性。
