Crystal architecture and thermal decomposition of two new organically templated cadmium sulfates

Two organic-inorganic hybrid compounds (C 5 H 14 N 2 )[Cd(H 2 O) 6 ](SO 4 ) 2 ( I ) and R-(C 5 H 14 N 2 )×[Cd(H 2 O) 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 SO 4 2− anions, disordered 2-methylpiperazinediium, (C 5 H 14 N 2 ) 2+ in compound I or R-2-methylpiperazinediium R-(C 5 H 14 N 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.