Variable dimensionality and framework found in a series of quaternary zinc selenites, A(2)Zn(3)(SeO3)(4)center dot xH(2)O (A = Na, Rb, and Cs; 0 <= x <= 1) and Cs2Zn2(SeO3)(3)center dot 2H(2)O

Abstract

Five new alkali metal zinc selenites, A(2)Zn(3)(SeO3)(4)center dot xH(2)O (A = Na, Rb, and Cs; 0 <= x <= 1) and Cs2Zn2(SeO3)(3)center dot 2H(2)O have been synthesized by heating a mixture of ZnO, SeO2 and A(2)CO(3) (A = Na, Rb, and Cs), and characterized by X-ray diffraction (XRD) and spectroscopic analyses techniques. All of the reported materials revealed a rich structural chemistry with different frameworks and connection modes of Zn2+. While Rb2Zn3(SeO3)(4) and Cs2Zn3(SeO3)(4)center dot H2O revealed three-dimensional frameworks consisting of isolated ZnO4 tetrahedra and SeO3 polyhedra, Na2Zn3(SeO3)(4), Cs2Zn3(SeO3)(4), and Cs2Zn2(SeO3)(3)center dot 2H(2)O contained two-dimensional [Zn-3(SeO3)(4)](2-) layers. Specifically, whereas isolated ZnO4 tetrahedra and SeO3 polyhedra are arranged into two-dimensional [Zn-3(SeO3)(4)](2-) layers in two cesium compounds, circular [Zn3O10](14-) chains and SeO3 linkers are formed in two-dimensional [Zn-3(SeO3)(4)](2-) layers in Na2Zn3(SeO3)(4). Close structural examinations suggest that the size of alkali metal is significant in determining the framework geometry as well as connection modes of transition metal cations.