ONE-DIMENSIONAL POLYMERIC CHLOROCADMATE(II) SYSTEMS OF N-METHYLPIPERAZINIUM AND N,N'-DIMETHYLPIPERAZINIUM COMPOUNDS - SYNTHESIS, STRUCTURALAND THERMAL-PROPERTIES

The chlorocadmate(II) systems of (H(2)me(2)pipz)[Cd2Cl6(H2O)(2)] (1) a nd (H(2)mepipz)(2)[Cd3Cl10(H2O)] (2) (L=me(2)pipz=N,N'-dimethylpiperaz ine; L'=mepipz=N-methylpiperazine) were prepared and their structural and thermal properties investigated. Compound 1 is monoclinic, space g roup P2(1)/c, a=7.664(1), b=7.472(4), c=15.347(1) Angstrom, beta-99.46 8(7)degrees, Z=2, R=0.024. The crystal structure consists of organic c ations and infinite one-dimensional chains of [CdCl3(H2O)](3-)(n) anio ns. Each Cd atom is octahedrally surrounded by bridged and terminal ch lorine atoms and by a water molecule, which is in trans position with respect to the terminal chlorine atom. Inter- and intrachain hydrogen bond interactions between the terminal chlorine atoms and the water mo lecules contribute to the crystal packing. Compound 2 is orthorhombic, space group Cmc2(1), a=15.286(3), b=13.354(3), c=13.154(3) Angstrom, Z=4, R=0.023. The crystal structure consists of organic dications and infinite chains of [Cd2Cl6(CdCl4H2O)](4-)(n) units running along the [ 001] axis. Each unit is formed of regularly alternate six-coordinated Cd atoms, one of them linking one pentacoordinated Cd atom which compl etes its coordination through a water molecule. A strong hydrogen bond interaction involving the organic dication and the inorganic chain co ntributes to the crystal packing. Differential scanning calorimetry me asurements did not show the presence of any structural phase transitio ns. The structures are compared with those of (H(2)pipz)[Cd2Cl6(H2O)(2 )] (3), (H(2)mepipz)[Cd2Cl6(H2O)(2)]. H2O (4) and (H(2)mepipz)[Cd2Cl6] (5) (L=pipz=piperazine,L'=mepipz=N-methylpiperazine).