【摘要】 在B3LYP/6-31++G**水平下,对氧化呋咱单体及二聚体进行了几何构型优化,发现在由单体结合形成二聚体的过程中,子分子的平面构型并没有发生改变。通过振动频率分析结果推测出,分子中形成较大的π-π共轭,对C-H键的振动频率有影响,使得C-H伸缩频率发生了略微的红移,强度也明显增强。分子中原子(atoms in molecular,AIM)理论得出C-H共价键键临界点处电子密度的Laplacian值■2ρ具有负值。而O…H与N…H键临界点处2ρ都是大于零的,表明氧化呋咱二聚体中的O…H与N…H符合一般氢键的拓扑特点。二聚体在C-H键临界点处聚积电子的能力增强。运用渐近修正的SAPT(DFT)方法(symmetry-adapted perturbationtheory employing density functional theory),对氧化呋咱二聚体分子间作用进行能量分割。其中二聚体的静电能分别为-30.10kJ.mol-1和-37.36kJ.mol-1,与总的作用能相当,这也从侧面反映了氧化呋咱二聚体中分子中氢键作用主要由静电能决定。更多还原

【Abstract】 Geometrical structures of furoxan monomer and dimers were optimized at the B3LYP/6-31++G level.It is found that the planar structure of sub molecule is not changed in the process of forming a dimer.Based on the frequency vibration results,it can be speculated that the π-π conjugation in the structure has influence on the C—H stretching.Consequently,the C—H stretching exhibits some red shifts and its intensity is strengthened.The ■2ρ at bond critical points(BCP)of C—H bonds are negative,contrary to those of O…H and N…H hydrogen bonds.It indicates that the O…H and N…H hydrogen bonds(HB)are accord with the common HB features.The capability of the dimers to concentrate electrons at BCP of C—H bonds enhanced.The recently developed aymptotically corrected symmetry-adapted perturbation theory,combined with density functional theory,was used to study the contributions of intermolecular interaction energy of furoxan as a simple model.The electrostatic energies of dimer Ⅰ and dimer Ⅱ are-30.10 kJ·mol-1 and-37.36 kJ·mol-1 respectively,which are equal to the total energies.It directly reflects that the HB interaction of furoxan is dominated by electrostatic energy.更多还原