非金属二元氢化物pk_a与量子化学参数的关系

A relationship between pk_a values and quantum-chemical descriptors of the hinary bydrides of the nonmetals

在HF/3-21G水平下,对13种非金属二元氢化物分子(HF,HCl,HBr,HI,H2O,H2S,H2Se,H2Te,NH3,PH3,AsH3,CH4和SiH4)进行了几何构型全优化和电子结构计算.将获得的电子结构数据与这些分子的pka值相关联,进行逐步回归分析.结果显示,pka与非氢原子的键价、分子的最低空轨道能间存在显著的二元线性相关性,相关系数R=0 994.pka计算值与实验值符合得较好.表明非金属二元氢化物中非氢原子的键价、分子的最低空轨道能在决定其酸性上起重要作用.

In this paper,the ab initio molecular orbital calculations at HF/3-21G level were adopted to study electronic structures of 13 binary hydrides molecules of the nonmetals including HF,HCl,HBr,HI,H2O,H2S,H2Se,H2Te,NH3,PH3,AsH3,CH4 and SiH4.Results showed there exists multivariate significant correlation between the calculated values of bonded valences,LUMO energies and pka values of the binary hydrides of the nonmetals.The bonded valences and lowest unoccupied orbital energies play an important role in determining the acidity of the binary hydrides of the nonmetals.