Brønsted acid sites in metal-containing solid acids: from quantification to molecular design of new catalysts/silver(I)-polyoxometalates.

Based on H/D isotope exchange studies devoted to the quantification of the number of Brønsted acid sites in solid acids, we report herein an innovative approach to determine the amount of silver cations present in Keggin-type polyoxometalates (POM). The molecular design of these bifunctional heteropolyacids can therefore be achieved by varying the Ag(+)versus H(+) exchange ratio in the starting mixture. Consequently, the stoichiometries of Ag(x)H(4-x)SiW₁₂O₄₀ POM were ascertained for 0 < x < 4 by the H/D exchange technique.