One-dimensional polymeric chlorocadmate(II) systems of N-methylpiperazinium and N, N′-dimethylpiperazinium compounds: synthesis, structural and thermal properties

Abstract

The chlorocadmate(II) systems of (H 2me 2pipz)[Cd 2Cl 6(H 2O) 2] ( 1) and (H 2mepipz) 2[Cd 3Cl 10(H 2O)] ( 2) (L = me 2pipz = N, N′-dimethylpiperazine; L′ = mepipz = N-methylpiperazine) were prepared and their structural and thermal properties investigated. Compound 1 is monoclinic, space group P2 1/c, a = 7.664(1), b = 7.472(4), c = 15.347(1) A ̊ , β = 99.468(7)°, Z = 2, R = 0.024 . The crystal structure consists of organic cations and infinite one-dimensional chains of [CdCl 3(H 2O)] n 3− anions. Each Cd atom is octahedrally surrounded by bridged and terminal chlorine 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 molecules 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) A ̊ , R = 0.023 . The crystal structure consists of organic dications and infinite chains of [Cd 2Cl 6(CdCl 4H 2O] n 4− 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 completes its coordination througha water molecule. A strong hydrogen bond interaction involving the organic dication and the inorganic chain contributes to the crystal packing. Differential hydrogen bond interaction involving the organic dication and the inorganic chain contributes to the crystal packing. Differential scanning calorimetry measurements did not show the presence of any structural phase transitions. The structures are compared with those of (H 2pipz)[Cd 2Cl 6(H 2O) 2] ( 3), (H 2mepipz)[Cd 2Cl 6(H 2O) 2]·H 2O ( 4) and (H 2mepipz)[Cd 2Cl 6] ( 5) (L = pipz = piperazine, L′ = mepipz = N-ethylpiperazine).