When neither of sulfate, selenate, and fluoroberyllate are isostructural analogs: the case of Cd[BeF4]·4H2O and (C2H8N2)[Cd(H2O)6][BeF4]2

Abstract

Single crystals of two new cadmium fluoroberyllates, Cd[BeF4]·4H2O (1) and (C2H10N2)[Cd(H2O)6][BeF4]2 (2), were isolated from products of reaction between CdO, H2[BeF4], and ethylenediamine. Compound 1 is monoclinic, C2/c, a = 9.4891(3), b = 6.3751(2), c = 10.7541(3) Å, β = 105.248(2)°; its crystal structure, based on [Cd(H2O)4/4(BeF4)2/2]0 chains, is totally dissimilar to those of most M(TO4)·H2O (M = Mg, Fe – Ni, Zn; T = S or Se) sulfates and selenates. 2 is also monoclinic, P21/n, a = 8.2702(3), b = 7.0248(3), c = 13.1620(4) Å, β = 101.710(3)°; it is isostructural to (C2H8N2)[Ni(H2O)6](SO4)2 but not analogous to the respective ethylenediammonium – cadmium sulfate and selenate. Therefore, the sulfates, selenates, and fluoroberyllates of both cadmium itself and cadmium – ethylenediammonium exhibit totally different crystal structures and hydration numbers. This is in vivid contrast to the recently discussed compounds of copper wherein both Cu(TX4)·5H2O and (C2H10N2)[Cu(H2O)4](TX4)2 compounds (TX4 = SO4, SeO4, and BeF4) form two isostructural groups.