卤素氮氧化物的结构和光谱性质的理论研究

Theoretical Studies on Structures and Spectroscopic Properties of Nitryl Halogenides

通过DFT B3LYP计算 ,优化了卤素氮氧化物XNO2 及其异构体XONO (X =F ,Cl,Br,I)的平衡几何构型 ,预测了异构体的相对稳定性及其相互转化的活化能垒 .在B3LYP和QCISD(T)计算水平上 ,确定了X—NO2 键的解离能 .应用与时间有关的密度泛函理论 (TD B3LYP)计算了XNO2 低激发态的跃迁能 。

Density functional theory with the B3LYP functional is used to calculate the equilibrium geometries and harmonic vibrational frequencies of nitryl halogenides XNO2 and XONO (X = F, Cl, Br, I). Stabilities and isomerizations of these isomers are investigated. Dissociation energies of the X-N bond in XNO2 are predicted at the B3LYP/6-311G* and QCISD(T)/ce-pvTZ levels. The electronic transition energies of the most stable XNO2 species have been estimated by time-dependent B3LYP calculations. The electron promotion of a nonbonding electron of the halogen atom X in XNO2 into a pi* orbital on the NO2 moiety, i.e., the n-->sigma* electron excitation, is responsible for the photodissociation of the X-N bond.