Acentric and Centric Interpenetrations of an Anionic Framework Mediated by Cation Sizes: The Alkali-Metal Tin(II) Benzenedicarboxylates A₂Sn₂(bdc)₃(H₂O)_<i>x</i> (A = Li, Na, K, Rb, Cs)

Abstract

A series of alkali-metal tin benzenedicarboxylates A2Sn2(bdc)3(H2O)x, A = Li, Na, K, Rb, Cs, in single crystal forms have been synthesized by using a hydrothermal technique. The compounds all have cubic crystal structures based on a very open anionic [Sn2(bdc)3]2− framework which is 8-fold interpenetrated noncentrosymmetrically (space group I23) in Li2Sn2(bdc)3(H2O)2, 1, K2Sn2(bdc)3, 3, Rb2Sn2(bdc)3, 4, and Cs2Sn2(bdc)3, 5, but centrosymmetrically (space group Pn3̅) in Na2Sn2(bdc)3(H2O), 2. The ion size and coordination requirements of the alkali ions play an important role in the interpenetration of the anionic framework and the symmetry of the structures.