Organically templated linear and layered cadmium sulfates

Abstract

By reacting cadmium salts with H₂SO₄ in the presence of organic amines or directly with amine sulfates under hydrothermal conditions, it has been possible to prepare three linear cadmium sulfates of linarite topology, with the compositions [H₃N(CH₂)₂NH₃]₂[CdCl₂(SO₄)][SO₄]·H₂O, I, [HN(CH₂)₆NH][CdBr₂(SO₄)], II, [HN(CH₂)₆NH][CdCl₂(SO₄)], III. A layered cadmium sulfate of composition [H₃N(CH₂)₃NH₃][Cd₂(H₂O)₂(SO₄)₃], IV, has also been obtained. These sulfates are the first examples of a family of organically templated metal sulfates with interesting structural features. In the linarite chains, the CdX₄O₂ (X=Cl, Br) octahedron shares two trans-edges to form an [Mφ₄] (φ=anionic ligand) chain decorated by the SO₄ tetrahedron that adopts a staggered arrangement on either side of the chain. IV is constructed by the fusion of four-membered ring ladders involving edge sharing between the sulfate tetrahedron and metal octahedron. IV appears to be the first member of a family of organically templated metal sulfates containing an octahedral-tetrahedral 2D net wherein the sulfate tetrahedron is connected at all four corners.