Relationships of electronic structures and physico-chemical properties of Keggin anions on central atoms

The electronic structures of Keggin - type heteropolyanions (XMo12O40)(n-) (X = B, Al, Si, Ge, P, As, S)have been calculated by the Density Functional Theory coupled with Discrete Variational Method (DFT-DVM). Based on the ca lculated results of the seven heteropoly anions, we discussed the influence of the central atoms on the electronic structure, stability, oxidizability and acidity. These results give the sequences of (1) stability, (2) acidit y and (3) oxidizability of seven heteropoly anions respectively, as follows : (1) (SMo12O40)(2-) > (AsMo12O40)(3-) > (PMo12O40)(3-) > (GeMo12O40)(4-) > (BMo12O40)(5-) > (SiMo12O40)(4-) > AlMo12- O-40)(5-); (2)H2SMo12O40>H3AsMo 12O40>H3PMo12O40>H4GeMo12O40>H4SiO12O40>H-5 AlMo12O40> H5BMo12 O-40; (3) (S Mo12O40)(2-) > (ASMo(12)O(40))(3-) > (PMo12O40)(3-) > (GeMo12O40)(4-) > (Si Mo12O40)(4-) > (AlMo12O40)(5-) > (BMo12O40)(5-). These sequences are strong ly supported by many experimental results.