The Influences of Skeleton Metal Atoms on Electronic Structures and Physical - Chemistry Properties of Keggin Anions

The electronic structures of Keggin anions (PM12O40)n- (M = Mo, W, V) ,(PMo9W3O40)3-(PMo9V3O40)6- have been calculated by the Discrete Variational Method coupled with the first principal Density Functional Theory (DFT- DVM). The influences of skeleton metal atoms on the charge distribution, bonding effects, stability, redox properties are discussed. The results show that skeleton metal atoms have influence on the charge distribution and bonding effects. The relative sequence of stability is: (PW12O40)3- (PMo12O40)3- (PV12O40)15-. We developed the two- factors method for determining the escape ability of lattice oxygen atoms and the LUMO electronegativity. The relative sequence of redox properties has then been shown to be: (PV12O40)15- (PMo12O40)3- (PW12O40)3-. The replacement effects of Mo with W and V are discussed. The stability of Keggin units is strengthened, but the redox ability is weakened when the Mo atoms are replaced by W. The stability is weakened and redox property is strengthened when the Mo atoms are replaced by V.