Salt-templated open frameworks (CU-2):: Novel phosphates and arsenates containing M3(X2O7)22- (M = Mn, Cu; X = P, As) micropores 5.3 Å and 12.7 Å in diameter

We have recently isolated a novel family of salt-templated phosphates and arsenates, A(2)M(3)(X2O7)2 .(salt) [where A = K, Rb, Cs; M = Mn, Cu; X = P, As]. The space-filling, charge-compensation alkali metal chloride salts can be removed conveniently without destroying the MXO framework; These materials (designated as CU-2-MXO) exhibit microporous structures (ca. 5.3 and 12.7 Angstrom in diameter) in which the active transition metal sites are distributed ina spatially uniform manner throughout the bulk. The salt lattice functions as a structure-directing template. The single-crystal structure shows that the large pore contains a remarkable ACl/CsCl lattice that Consists of two interpenetrating; square antiprismatic columns of ions. In contrast to organically templated microporous solids, these new materials were synthesized by conventional solid-state reactions at high temperatures. Consequently, the resulting compounds can endure extensive heating to ca. 650 degrees C. These materials, in fact, possess the highest thermal stability found thus far among zeolite and related materials. Along with the synthesis and structure of four CU-2-MXO compounds, we also report some preliminary results concerning studies of ion-exchange and topotactic deintercalation-intercalation reactions.