Disodium tricopper(II) tetra-kis[selenate(IV)] tetra-hydrate

Abstract

The title compound, Na2Cu3(SeO3)4(H2O)4, has been prepared under hydro-thermal conditions. The crystal structure contains a three-dimensional anionic framework made up from distorted [CuO4(H2O)2] octa-hedra ( symmetry), [CuO4(H2O)] square pyramids and trigonal-pyramidal SeO3 units sharing common corners. The connectivity among these units leads to four- and eight-membered polyhedral rings, which by edge-sharing inter-connect into walls. A rhombus-like 16-membered polyhedral ring channel system with a longest length of approximately 14.0 Å and a shortest length of 5.3 Å is enclosed by such walls along the a axis. The water mol-ecules attached to the Cu atoms, as well as the electron lone pairs of the SeIV atoms, protrude into these channels. The seven-coordinated Na+ counter-cations occupy the remaining free space of the 16-membered polyhedral ring channels. An intricate network of O - H⋯O hydrogen bonds further consolidates the three-dimensional structure.