When sulfate, selenate, and fluoroberyllate are not 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)·4H2O (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.