Copper (II) substituted heteropoly molybdate and tungstate of the keggin type anion [Xn+M12O40]-(8-n) : Their synthesis and characterization

Abstract

Two heteropoly oxometalates with molecular formula Na6[CuIIMoVI 12O40].14H2O(1) and Na6[CuIIWVI 12O40].11H2O(2) having Keggin type anion [Xn+M12O40]-(8-n) have been synthesized in which the central XO4 tetrahedra are repl- aced by CuO4.The compound [1] is prepared from aqueous solution of Na2MoO4.2H2O and CuCl2.2H2O at pH =4.5 and the compound[2] from an aqueous solution of Na2WO4.2H2O and CuCl2.2H2O at pH = 4.9.The elemental analyses predict 1:12 atomic ratio of the heteroatom (CuII) to the addenda Mo and W respectively. The peaks in the IR studies for both the compound are in good agreement with the proposed formulae. The stretching of Cu-O bands occupy at higher frequencies than that for the Anderson anion which is due to lower coordination number of copper atom. The compounds are further characterized by thermal analyses and mole-cular weight determination.