Theoretical Study of the Relative Stabilities of the alpha /beta 3-[XW11O39]m- Lacunary Polyoxometalates (X = P, Si).
Résumé
A computational DFT-B3PW91 study of the relative stability of the monolacunary Keggin polyoxotungstates alpha and beta 3-[XW11O39]m- (X = P, m = 7; X = Si, m = 8) was performed. The influence of the nature of different grafted cations and of the central anion XO4n- on the relative stabilities of the lacunary isomers was analyzed. From these results, an interpretation of the structural difference in the metallic frameworks of alpha -[PW11O39{Ru(DMSO)3(H2O)}]5-, alpha -[PW11O39{Ru(C6H6)(H2O)}]5-, and beta 3-[SiW11O39{Ru(DMSO)3(H2O)}]6- is proposed, and conclusions are drawn as to how to favor the formation of beta 3 derivs. in future syntheses.