电场中R-NO_2…HF(R=-CH_3、-NH_2、-OCH_3)氢键复合物结构及性能的理论研究

Theoretical studies on the structures and properties of R- NO_2…HF( R =- CH_3、- NH_2、- OCH_3) in electric field

采用密度泛函B3LYP方法,在6-311++G(2d,p)水平上对外电场中的R-NO_2(R=-CH_3、-NH2、-OCH3)及其HF氢键体系(R-NO2…HF)进行了结构优化,然后在6-311++G(2d,p)和aug-cc-p VTZ基组水平上分别用B3LYP和MP2(full)方法进行了能量计算,并对单体R-NO_2在CCSD(T)方法下进行了更为详细的考量,最后借助分子中的原子(AIM)理论以及分子静电势揭示了结构和能量变化的本质.结果表明,在一定方向和大小的外电场作用下,单体分子的相对总能量降低,引发键键长变短,偶极矩增大,引发键离解能变大;氢键复合物比其单体引发键键长更短,引发键键能也更大.

Fully optimized geometries of R - NO2 （ R = - CH3 , - NH2 , - OCH3 ） and R - NO2..- HF complexes in external electric field have been obtained with B3LYP methods at the 6 -311 ＋ ＋ G（2d, p） level. And the energies have been calculated by the B3LYP and MP2（full） methods at the 6 -311 ＋ ＋ G（2d,p） and aug -cc -pVTZ levels, especially for the ones of monomer molecules by the CCSD（T） method for more details. The na- tures of differences between structures and properties have been revealed by the analysis of AIM and molecular e- lectrostatic potential exploratory. The results indicate that the molecular relative energies and the bond lengths of the solicitation bond decrease while the dipole moment and the bond dissociation energies increase in a certain rate and direction of electric field. What＇ s more, the bond lengths of the solicitation bond become shorter and the bond dissociation energies bigger when the monomer molecules become intermolecular hydrogen - bonded complex.