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Journal of Structural Chemistry

2013 year, number 6

CRYSTAL ARCHITECTURE AND THERMAL DECOMPOSITION OF TWO NEW ORGANICALLY TEMPLATED CADMIUM SULFATES

R. Jlassi1, W. Rekik1, H. Naïli1, T. Mhiri1, T. Bataille2
1Laboratoire Physico-Chimique de l'état Solide, Département de Chimie, Faculté des Sciences de Sfax, Université de Sfax, Sfax, Tunisia
2Sciences Chimiques de Rennes (CNRS, UMR 6226), Université de Rennes 1, Rennes Cedex, France
Keywords: hybrid material, slow evaporation, X-ray diffraction, crystal structure, thermal decomposition, supramolecular

Abstract

Two organic-inorganic hybrid compounds (C 5H 14N 2)[Cd(H 2O) 6](SO 4) 2 (I) and R-(C 5H 14N 2) [Cd(H 2O) 6](SO 4) 2 (II) are synthesized by the slow evaporation method and characterized by single crystal X-ray diffraction, thermogravimetry, temperature-dependent X-ray diffraction, and infrared spectroscopy. The first compound crystallizes in the centrosymmetric space group P 2 1/ n with the following unit cell parameters: a = 6.6208(2) Å, b = 10.6963(3) Å, c = 12.9318(4) Å, V = 893.05(6) Å 3, and Z = 2. Its structure is solved by direct methods and refined by the least-squares analysis [ R 1 = 0.0389 and wR 2 = 0.0821]. This compound shows a crystallographic disorder II destroys the inversion symmetry and leads to a fully ordered structure. Indeed, compound II crystallizes in the non-centrosymmetric space group P 2 1 with the following unit cell parameters: a = 6.6306(1) Å, b = 10.7059(2) Å, c = 12.9186(1) Å, V = 894.67(2) Å 3, and Z = 2. The crystal structure of both compounds is built from isolated anions, disordered 2-methylpiperazinediium, (C 5H 14N 2) 2+ in compound I or R-2-methylpiperazinediium R-(C 5H 14N 2) 2+ in compound II, and divalent metal cations surrounded by six water molecules. These different entities are connected together only by a 3D hydrogen bond network. The thermodiffractometry and the thermogravimetric analyses indicate that the decomposition of the supramolecular precursors proceeds through several stages leading to cadmuim oxide.