Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry 605 008, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2011 Dec 15;84(1):196-209. doi: 10.1016/j.saa.2011.09.029. Epub 2011 Sep 20.
Experimental FTIR, FT-Raman and FT-NMR spectroscopic studies of o-fluoronitrobenzene and p-fluoronitrobenzene have been carried out. A detailed quantum chemical calculations have been performed using DFT/B3LYP method with 6-311++G** and 6-31G** basis sets. Complete vibrational analyses of the compounds were performed. The temperature dependence of thermodynamic properties has been analysed. The atomic charges, electronic exchange interaction and charge delocalisation of the molecule have been performed by natural bond orbital (NBO) analysis. Molecular electrostatic surface potential (MESP), total electron density distribution and frontier molecular orbitals (FMOs) are constructed at B3LYP/6-311++G** level to understand the electronic properties. The charge density distribution and site of chemical reactivity of the molecules have been obtained by mapping electron density isosurface with electrostatic potential surfaces (ESP). The electronic properties, HOMO and LUMO energies were measured by time-dependent TD-DFT approach. (1)H and (13)C NMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecule were calculated. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecules in chloroform solvent and in gas phase were calculated by using the Gauge-Independent Atomic Orbital (GIAO) method and are found to be in good agreement with experimental values. The theoretical parameters obtained at B3LYP levels have been compared with the experimental values.
对邻氟硝基苯和对氟硝基苯进行了实验的 FTIR、FT-Raman 和 FT-NMR 光谱研究。使用 DFT/B3LYP 方法，结合 6-311++G和 6-31G基组，进行了详细的量子化学计算。对化合物进行了完整的振动分析。分析了热力学性质的温度依赖性。通过自然键轨道 (NBO) 分析，对分子的原子电荷、电子交换相互作用和电荷离域进行了研究。在 B3LYP/6-311++G**水平上构建了分子静电表面势 (MESP)、总电子密度分布和前沿分子轨道 (FMOs)，以了解电子性质。通过映射电子密度等位面与静电势表面 (ESP)，获得了分子的电荷密度分布和化学反应活性位点。通过时间相关 TD-DFT 方法测量了电子特性、HOMO 和 LUMO 能量。记录了 (1)H 和 (13)C NMR 谱，并计算了分子的 (1)H 和 (13)C 核磁共振化学位移。使用无标度原子轨道 (GIAO) 方法，计算了分子在氯仿溶剂和气相中的 (1)H 和 (13)C 核磁共振 (NMR) 化学位移，并与实验值吻合良好。在 B3LYP 水平上获得的理论参数与实验值进行了比较。
