Ionothermal Synthesis of Cadmium Coordination Polymers: Ionic Liquid Effects on the Synthesis, Structural, and Thermal Characterization

Abstract

Ionothermal synthesis is a little used method for the preparation of coordination polymers. By this method, two cadmium compounds were synthesized, 1, with formula Cd-3(ox)F-2(Ina)(2) (Ina = isonicotinate) and 2, Cd(NO3)(2)(4,4 ' -Bpy) (4,4 ' -Bpy = 4,4 ' -Bipyridine). The modification of the reaction conditions has allowed to obtain 2 as a pure phase. The structure of both compounds was determined by a single-crystal X-ray diffraction. Compound 1 is isostructural to the previously reported Cd2Zn(ox)(OH)(2)(Ina)(2). It crystallizes in the monoclinic space group P2(1)/n and present a three-dimensional (3D) network, built-up from [Cd-3(ox)F-2](n)(2n+) layers, linked by isonicotinate ligands. Crystals of 2 are formed by twins of two components which are rotated ca. 180 degrees to each other. This compound crystallizes in the triclinic P-1 space group and its structure can be describe as a two-dimensional (2D) 4 connected 'sql' net. The layers are composed by [Cd(NO3)(2)](n) chains linked through 4,4 ' -Bpy ligands, and are pillared along the [011] direction. The thermal decomposition of 2 was studied by thermogravimetric and thermodiffractiometric techniques. The compound decomposes gradually starting from 160 degrees C, and due to heating, the structure suffers slight reversible changes in the bond distances and angles.