锌族和钛族卤化物振动光谱的理论计算

采用ab initio RHF,MP2和B3LYP方法以及LanL2DZ和SDD基组计算了四面体锌族卤素阴离子化合物(MX₄^2-,M=Zn(Ⅱ),Cd(Ⅱ),Hg(Ⅱ);X=F^-,Cl^-,Br^-,I^-)和钛族卤化物(MX₄,M=Ti(Ⅳ),Zr(Ⅳ),Hf(Ⅳ);X=F^-,Cl^-,Br^-,I^-)的几何构型和振动频率。计算结果表明,LanL2DZ基组是合适的基组,能得到合理的电荷分布,几何参数以及振动频率。在锌族卤化物的计算中发现,角弯曲振动频率与实测值相当一致,键伸缩振动频率略为偏低,这主要是由于计算的键长略为偏长所致。MP2方法计算的振动频率更接近于实测值。在钛族卤化物的计算中,三种计算方法都相当地再现了实测值,而以B3LYP方法更为满意。

Theoretical Calculation of Vibrational Frequencies for Halides of Zinc and Titanium Groups

The geometries and vibrational freq uencies of halide anions of zinc grou p(MX 42-,M=Zn?,Cd?,Hg ?;X =F-,Cl-,Br-,I-)and halides of titanium group(MX 4 ,M=Ti ?,Zr ?,Hf ?;X =F-,Cl-,Br-,I-)have been theoretically calculated using ab initio RHF,MP2and B3LYP methods with LanL2DZ and SDD basis sets.The results calculated revealed that LanL2DZ basis set is a satisfi ed one for obtaining reasonable popu lation of charge on the metals,geometry param eters and vibrational frequencies.In MX 42-compounds,it was found that the calc ulated frequencies of the bent vibra tions associated with angles are in good agreement with the experimental values,and the frequencies o f bond stretching are lower than that of observation,due to the overestimation of bond lengths.The vibrational frequencies calculated at MP2/LanL2DZ level are more reached to the experim ental values.In MX 4 compounds,three methods with same L anL2DZ basis set reappeared the measured values with a sufficient accuracy,and more satisfied results are obtained with B3LY P method.