SYNTHESIS AND CHARACTERIZATION OF ONE-DIMENSIONAL POLYMERIC CHLOROCADMATE(II) SYSTEMS

In this paper we report the synthesis and the structural, thermal, electrical properties of 1-D polymeric chlorocadmates(II), having N-methylpropane-1,3-diammonium (mepnH2) and NN-diethylpropane-1,3-diammonium (et2pnH-2) as countercations. The (mepnH2)2[Cd3CI10] crystallizes in space group P2(1)/c. The unit cell dimensions are a = 10.164 (3) angstrom, b = 13.434 (10) angstrom, c = 10.099 (3) angstrom, beta = 112.04 (3)-degrees, V = 1278 (i) angstrom3, z = 2. The final R value for 2124 reflections (I > 2sigma(I)) is 0.0445 (R(w) = 0.0384). Its structure consists of N-methylpropane-1,3-diamine dications and infinite chains of [(Cd3Cl10)n4n-]n moieties forming 1-D polymer running along the x axis. The (et2pnH2)2[Cd5Cl14].2H2O crystallizes in space group P1BAR. The unit cell dimensions are a = 6.874 (1) angstrom, b = 10.381 (1) angstrom, c = 14.572 (i) angstrom, a = 100.14 (1)-degrees, beta = 99.31 (1)-degrees, gamma = 97.46 (1)-degrees, V = 996.7 (2) angstrom3, Z = 1. The final R value for 3405 reflections (I > 2sigma(I)) is 0.0452 (R(w) = 0.0393). Its structure consists of N,N-diethylpropane-1,3-diamine dications, infinite alternate stacked pseudoplanar trinuclear [Cd3Cl8]2- and dinuclear [Cd2Cl6]2- dianions and uncoordinated water molecules. Both the packings are strengthened by N-H ... Cl hydrogen bonds between anions and cations. A first-order phase transition of (mepnH2)2[Cd3CI10] has been identified by DSC measurements and X-ray powder diffraction, related to the disordering of the hydrocarbon chains at high temperature. This increases the cell volume. The electrical conductivity of the compounds can be envisaged as protonic, and the whole electrical behavior can be correlated to their structures and phase transition.