Abstract: Tomasi′s Polarized Continuum Model(PCM) and ab initio method were applied to calculate quantum chemical parameters for H_mA in water. Seven quantum chemical parameters, which were correlated with electronic density of the center atom A, were used to derive two equations of QSPR for the pK_a of H_mA by multiple linear regression(MLR) and stepwise regression(SR) respectively, and the correlated coefficient R and standard derivation s of the MLR and SR equations are 0.9984, 0.9947 and 1.7349, 2.3618, respectively. By the leave-one-out method prediction, the R and s of MLR and SR equation are 0.9689, 0.9895 and 7.5985, 3.3118, respectively. The results show that the SR equation, which is composed of three parameters, is the best in prediction, and the three parameters, NC(Net Charge), TP(Total Population) and E_LUMO are the key factors affecting the acid intensity of H_mA. The physical meaning and the influence of the three parameters on pK_a of H_mA were investigated. The study indicates that NC, TP and E_LUMO are the main factors which affect the electronic density of center atom A; E_LUMO and TP are the decisive factors affecting the change of acid intensity of H_mA in the same group and period respectively.

Key words: Nonmetal hydride, pK_a, Polarized continuum model, Ab initio, Electron density, Quantitative structure property relationship(QSPR)