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

The crystal structures of two polymeric 1-D linear-chain piperidinium and morpholinium trichlorocadmates(II) have been determined. The CdCl3(pdH) (pdH = piperidinium cation) salt is orthorhombic with the following space group and lattice constants: Ama2, a = 6.770(1) Å, b = 18.421(6) Å, c = 7.642(1) Å, Z = 4. Its structure consists of piperidinium cations and polymeric 1-D endless chains of triangular-face sharing distorted octahedral (CdCl6)4− ions, joined via three bridging chlorine atoms. The CdCl3(mfH) (mfH = morpholinium cation) salt is orthorhombic with the following space group and lattice constants: P212121, a = 17.524(4) Å, b = 14.368(3) Å, c = 7.000(1) Å, Z = 4. Its structure consists of zwitterionic 1-D linear Cd2Cl6(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 CdCl4(cis-Cl2) and CdCl4(cis-O2) distorted octahedra share edges by two chlorine atoms, forming chains of Cd2Cl6(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 CdCl3(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.