Maria Rita Cramarossa

Design, synthesis, structural and thermal characterisation of polymeric chlorocadmate(II) compounds with one-dimensional inorganic chain structures

Abstract The chlorocadmate(II) compounds of formula (Hmepd) [CdCl3] (1) (Hmepd = 1-methylpiperidine cation). (H2meen)2[Cd2Cl8] ∗d H2O (2) (H2meen = N-methylethylenediamine dication) and (H2amepz) [Cd2Cl6(H2O)2] (3) (H2amepz = 1-amino-4-methylpiperazine dication) are synthesised and their structural and thermal properties investigated. Compound 1 crystallises in space group P2/a. The unit cell dimensions are a = 15.046(2), b = 10.408(2) and c = 6.786(3) A , β = 92.39(2)°, Z = 4 . The final R value is 0.0353 (Rw = 0.0328). Its structure consists of one-dimensional polymeric chains of face-sharing CdCl6 octahedra running along the c axis and methylpiperidinium cations. Compound 2 crystallises in the C2/a space group. The unit cell dimensions are a = 18.459(2), b = 6.986(3) and c = 18.167(2) A , β = 115.95(2)°, Z = 4 . The final R value is 0.0296 (Rw = 0.0330). Its crystal structure consists of polymeric chains of [CdCl4]2− anions running along the b axis, organic cations and non-coordinated water molecules. Compound 3 crystallises in the P2/a space group, with a = 7.542(2), b = 14.568(4) and c = 8.052(2) A , β = 106.91(3)°, Z = 2. . The final R value is 0.330 (Rw = 0.340). The crystal structure consists of organic cations and polymeric chains of edge-sharing CdCl5(H2O) octahedra. In compounds 1 and 2 hydrogen bond interactions between the inorganic chains, the organic cations and the water molecules, if present, contribute to the crystal packing, while in compound 3 this contribution comes from the contact less than 3.5 A. The thermal characterisation is also discussed. The structures are composed with other examples of chlorocadmate(II) compounds.

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

The chlorocadmate(II) systems of (H2me2pipz)[Cd2Cl6(H2O)2] (1) and (H2mepipz)2[Cd3Cl10(H2O)] (2) (L = me2pipz = N,N′-dimethylpiperazine; L′ = mepipz = N-methylpiperazine) were prepared and their structural and thermal properties investigated. Compound 1 is monoclinic, space group P21/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 [CdCl3(H2O)]n3− 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 Cmc21, 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 [Cd2Cl6(CdCl4H2O]n4− 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 (H2pipz)[Cd2Cl6(H2O)2] (3), (H2mepipz)[Cd2Cl6(H2O)2]·H2O (4) and (H2mepipz)[Cd2Cl6] (5) (L = pipz = piperazine, L′ = mepipz = N-ethylpiperazine).

Trans-2-styrylbenzothiazole complexes with mercury(II) halides. Synthesis, characterization and X-ray crystal structure of diiodobis(trans-2-styrylbenzothiazole)mercury(II)

Abstract The synthesis of trans-2-styrylbenzothiazole (L) and of its complexes with mercury(II) halides is reported. Complexes with the formulae [Hg2(L)Cl4], [Hg(L)Br2], [Hg(L)2I2] and [Hg(L)I2] were isolated and characterized by conventional chemical analysis, electronic and IR spectra and by thermal analysis. For one of these complexes, [Hg(L)2I2], the X-ray crystal structure was also determined. The complex consists of discrete [Hg(L)2I2] units in which mercury, located on a two-fold axis, shows a distorted tetrahedral coordination and the ligand molecules are bonded via nitrogen atoms with HI = 2.61(2) A and HgN = 2.36(1) A bond distances.

SYNTHESIS, THERMAL AND ELECTRICAL CHARACTERIZATION OF 2-METHYLPENTANE-1,5-DIAMMONIUM TETRACHLOROCADMATE(II) WITH PEROVSKITE-LIKE STRUCTURE

Abstract This paper repotts the synthesis and the structural, thermal and electrical characterization of the 2-methyl-pentane-1,5-diammonium bidimensional chlorocadmate(II) system with perovskite-like structure. Its structure consists of layers of CdCl6 corner-sharing octahedra extending in the ab plane. Interposed sheets of organic dications link adjacent layers through hydrogen bonding and contribute to the crystal packing. The presence of a methyl group on the C(4) atom of the organic chain is considered responsible for the thermal stability of the compound between room and melting temperature (605 K). The compound behaves as an electrical insulator at low temperature approaching semiconducting values at higher temperature. These results are also compared with those found for other structurally similar compounds.

Synthesis and structural, thermal and electrical properties of piperazinium lodocuprates(I)

The iodocuprate(I) systems [H2pipz]2[Cu2l6]·H2O 1 and [H2pipz][Cu2l4]2(L = pipz = piperazine) have been prepared and their structural, thermal and electrical properties investigated. Compound 1 is monoclinic, space group P21/n, a= 8.609(3), b= 20.072(4), c= 13.763(4)A, β= 101.3(1)°, Z= 4, R= 0.050. The crystal structure consists of organic cations, unco-ordinated water molecules and dimeric [Cu2l6]– anions composed of two Cul4 tetrahedra sharing a common edge. Hydrogen bonds between organic counter cations and water molecules are present. Compound 2 is triclinic, space group P, a= 7.559(3), b= 7.465(3), c= 6.826(3)A, α= 68.1(1), β= 69.1(1), γ= 89.4(1)°, Z= 1, R= 0.050. The crystal structure consists of organic dications and infinite chains of [Cul2]– units forming a one-dimensional polymer running along the [001] axis. The chains are composed of edge-sharing Cul4 tetrahedra. Hydrogen-bond interactions between organic counter cations and inorganic chains are present and contribute to the crystal packing. Differential scanning calorimetry measurements did not show the presence of any structural phase transitions. Electrical measurements revealed an essentially ionic mechanism of conduction, especially at high temperature, protons involved in the hydrogen bonds being the charge carriers.

Cyclophanes:metal:arene ternary compounds: synthesis, crystal structure and spectroscopic properties of Bi2Br6:[2,2]paracyclophane:pyrene

Abstract In this paper we report the synthesis of a metal: [2,2]paracyclophane:arene ternary compound of formula Bi2Br6:[2,2]paracyclophane:pyrene. The compound is characterised by elemental and thermal analysis, by electronic and IR spectroscopy and conductivity measurements in the solid state. The structure was determined by single-crystal X-ray diffraction analysis: it consits of hexacoordinated bismuth atoms having in the nearest coordination sphere three bromines at 2.587(3), 2.635(4) and 2.656(3) A, two additional adjacent bromines at 3.353 (4) and 3.409 (3) A of different polyhedra and one phenyl group of a [2,2]paracyclophane molecule. The latter bridge bismuth atoms connecting linear (BiBr3)n polymeric chains giving a two-dimensional network including pyrene; the layers are packed by C…C and C…Br van der Waals contacts.