Polymeric 1-D linear-chain piperidinium and morpholinium trichlorocadmates (II): Synthesis and structural, thermal and electrical properties

Abstract

The crystal structures of two polymeric 1-D linear-chain piperidinium and morpholinium trichlorocadmates(II) have been determined. The CdCl 3(pdH) ( pdH = piperidinium cation) salt is orthorhombic with the following space group and lattice constants: A ma2, a = 6.770(1) A ̊ , b = 18.421(6) A ̊ , c = 7.642(1) A ̊ , Z = 4. Its structure consists of piperidinium cations and polymeric 1-D endless chains of triangular-face sharing distorted octahedral (CdCl 6) 4− ions, joined via three bridging chlorine atoms. The CdCl 3(mfH) ( mfH = morpholinium cation) salt is orthorhombic with the following space group and lattice constants: P212121 , a = 17.524(4) A ̊ , b = 14.368(3) A ̊ , c = 7.000(1) A ̊ , Z = 4. Its structure consists of zwitterionic 1-D linear Cd 2Cl 6(mfH) 2 chains in which two unequivalent cadmium atoms, Cd(1) surrounded by six chlorine atoms and Cd(2) by four chlorine atoms and two oxygen coordinated morpholinium cations, are present. Alternate CdCl 4(cis-Cl 2) and CdCl 4(cis-O 2) distorted octahedra share edges by two chlorine atoms, forming chains of Cd 2Cl 6(mfH) 2 units, running along the z axis. The compounds are also investigated by means of thermal, optical microscopy, X-Ray powder spectra and d.c. and a.c. electrical measurements. In particular for the CdCl 3(mfH) salt the two phase transitions appearing at 201 and 211°C are tentatively explained on the basis of the above cited measurements. Correlations among the different parameters and the known structures of these materials are also drawn.