1,720,966 research outputs found
CHARACTERIZATION OF THE BISMUTH(III) BROMIDE-[2.2]-PARACYCLOPHANE (2/1) ADDUCT
No full textThe 2:1 charge-transfer molecular complex between bismuth bromide and [2.2]paracyclophane has been prepared and investigated by means of thermogravimetric, electronic and IR spectra and resistivity measurements. The X-ray structure was also determined: monoclinic, space group P2(1)/c, a = 7.896(3), b = 14.198(6), c = 10.803(8) angstrom, beta = 101.27(5)-degrees, Z = 2 and R = 0.0457. The structure is built up by polymeric linear chains of BiBr3 units interlayered by centrosymmetric hydrocarbon molecules. Two bromine atoms bridge adjacent metal atoms so that the co-ordination is very distorted octahedral with three short [2.595(3)-2.676(3) angstrom] and two longer bridging [3.325(3), 3.402(2) angstrom] Bi-Br bonds; the sixth site is occupied by a benzene ring of the [2.2]paracyclophane molecule. The complex shows high stability and characteristic electrical properties of a semiconductor at 25-degrees-C
[N(2-AMMONIUMETHYL)PIPERAZINIUM]TETRACHLOROMONOBROMOCUPRATE(II) MONOHYDRATE - A COMPOUND CONTAINING A DISCRETE SQUARE-PYRAMIDAL UNIT
No full textThe crystal and molecular structure of the [N(2-ammoniumethyl)piperazinium]tetrachloromonobromocuprate(II) monohydrate is reported. The crystals are monoclinic, space group P2(1)/c, Z = 4, with a = 9.560(2), b = 9.240(3), c = 18.270(7) angstrom, beta = 99.20(2)degrees. The structure consists of discrete N(2-ammoniumethyl)piperazinium cations, uncoordinated water molecules and [CuCl4Br]3- anions, in which four coplanar chlorine atoms occupy the square-basal plane and one bromine atom the axial position, giving the copper(II) ion a moderately elongated square-pyramidal geometry. The structure was refined to a final R index of 0.0765
SYNTHESIS AND CHARACTERIZATION OF BISMUTH BROMIDE ARENE-PI COMPLEXES - X-RAY STRUCTURE OF BISMUTH(III) BROMIDE FLUORANTHENE-PARA-XYLENE (4/2/1)
No full textA structural and spectroscopic investigation of a charge-transfer complex of bismuth(III) bromide with fluoranthene is reported. Charge-transfer spectra of some complexes formed by BiBr3 with a series of polycyclic benzenoid and non-benzenoid hydrocarbons were recorded. The charge-transfer band energies, Ec.t., and the ionization potentials of the electron donors are linearly correlated with a slope of one. A linear correlation is also observed for Ec.t. and the first –* singlet transition energies of the benzenoid hydrocarbons. The crystal and molecular structure of bismuth (III) bromide–fluoranthene–p-xylene (4/2/1) was determined: crystals are triclinic, space group P, with a= 9.812(6), b= 11.199(7), c= 12.861 (8)Å, = 71.59(6), = 80.28(6), = 74.38(7)°, Z= 2, and R= 0.0848. The structure is formed by tetrameric Bi4Br12 centrosymmetric units in which three bromine atoms bridge adjacent bismuths, which show distorted octahedral co-ordination having five sites occupied by bromines and the sixth by a benzene ring of the fluoranthene at longer distances
SYNTHESES AND SPECTROSCOPIC PROPERTIES OF HALOCADMATES(II) - CRYSTAL AND MOLECULAR-STRUCTURE OF A NEW TRIBROMO[N-BENZYLPIPERAZINIUM]CADMIUM(II) COMPOUND
No full textTRANS-2-STYRYLBENZOTHIAZOLE COMPLEXES WITH MERCURY(II) HALIDES - SYNTHESIS, CHARACTERIZATION AND X-RAY CRYSTAL-STRUCTURE OF DIIODOBIS(TRANS-2-STYRYLBENZOTHIAZOLE)MERCURY(II)
No full textThe 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 Hg-I = 2.61(2) angstrom and Hg-N = 2.36(1) angstrom bond distances
STRUCTURAL, THERMAL, AND ELECTRICAL CHARACTERIZATION OF BIS(ETHYLETHYLENE)DIAMMONIUM DICHLORIDE TETRACHLOROCADMATE(II) WITH PEROVSKITE-LIKE STRUCTURE
No full textThe synthesis, thermal and electrical characterization of a chlorocadmate(II) system with perovskite-like structure of formula (etenH-2)2[CdCl4].Cl2 (etenH-2 = ethylethylenediamine dication) are described. The compound crystallizes in space group P2(1)/c. The unit-cell dimensions are a = 19.214(1) angstrom, b = 7.301(1) angstrom, c = 7.227(3) angstrom, beta = 100.23(1)-degrees, V = 997.7(4) angstrom3, Z = 2. The final R value is 0.0486 (R(w) = 0.0497). The crystal structure consists of inorganic layers of (CdCl6) corner-sharing octahedra, organic dications intercalated between them and uncoordinated chloride ions. Only one end of the organic dications interact via hydrogen bonds with the inorganic layers, with the second end involved in hydrogen bonds with the free chloride ions. Furthermore a network of hydrogen bond interactions among the inorganic layers, the organic dications, and the uncoordinated chlorine atoms contribute to the crystal packing. The compound, thermally stable up to the melting point, behaves as an electrical insulator at low temperatures, approaching semiconductor values at higher ones
SYNTHESIS, ELECTRON-PARAMAGNETIC RESONANCE AND X-RAY STRUCTURE CHARACTERIZATION OF COPPER(II) TERNARY COMPLEXES OF P-AMINOBENZOIC AND 3,4-DIMETHOXYHYDROCINNAMIC ACID WITH PHENANTHROLINES
No full textDimers of the type [Cu(pAb)(phen)(H2O)]2(NO3)2.2pAbH.2H2O (1) and [Cu(DPP)(4,7-phen)(H2O)]2(NO3)2.2H2O (2) (pAbH = p-aminobenzoic acid, DPPH = 3,4-dimethoxhydrocinnamic acid, phen = 1, 10-phenanthroline and 4,7-phen = 4,7-dimethyl-1, 10-phenanthroline) have been synthesized and characterized by means of EPR spectra in the solid and liquid states at room and low temperature, by magnetic measurements and by X-ray structure (1). Antiferromagnetic coupling of the unpaired electrons on each copper atom is evidenced by EPR spectra for both the compounds. They are, in fact, characteristic of dimers in which bridging nitrogen ligands are present. The Cu-Cu distance is 3.060 (1) angstrom and the dimer results through the bridging of two symmetry-related pAb molecules by bidentate carboxylic groups. The two phenanthroline molecules in the dimer are stacked with a minimum distance of 3.39 (1) angstrom
POLYNUCLEAR CHLOROCADMATE(II) COMPOUNDS WITH RIBBON-LIKE STRUCTURES - SYNTHESIS, STRUCTURAL CHARACTERIZATION AND THERMAL-BEHAVIOR
No full textIn this paper we report the synthesis and the structural characterization of two polynuclear chlorocadmate(II) systems with ribbon-like structure of formula (H(2)eten)[Cd2Cl6] . H2O (H(2)eten = ethylethylenediamine dication) and (Hetpipd)(2)[Cd5Cl12(H2O)(2)] . H2O (Hetpipd = 1-ethylpiperidine cation), respectively. (H(2)eten)[Cd2Cl6] . H2O crystallizes in space group P2(1)/a. The unit cell dimensions are a = 16.910(2), b = 13.570(2), c = 6.701(3) Angstrom, beta = 94.93(2)degrees, V = 1532(1) Angstrom(3), Z = 4. The final R value is 0.029 (R(w) = 0.028). Its structure consists of organic dications, polymeric ribbons formed by two infinite zig-zag chains running along the z axis linked by a common edge between adjacent octahedra and uncoordinated water molecules. The (Hetpipd)(2)[Cd5Cl12(H2O)(2)] . H2O crystallizes in space group C2/c. The unit cell dimensions are a = 26.811(2), b = 6.643(3), c = 21.724(2) Angstrom, beta = 111.25(3)degrees, V = 3606(2) Angstrom(3), Z = 4. The final R value is 0.039 (R(w) = 0.045). Its structure consists of alternate trinuclear [Cd3Cl6(H2O)(2)] and dinuclear [Cd2Cl6](2-) units, forming polymeric ribbons, organic cations and uncoordinated water molecules. Both packings are strengthened by hydrogen-bond interactions between anions and cations. The thermal properties for both compounds are discussed
TERNARY COPPER(II) COMPLEXES WITH 2,2'-BIPYRIDINE AND N-TOSYL-SUBSTITUTED AMINO-ACIDS .1. POLAROGRAPHIC AND PH-METRIC STUDY
No full textTERNARY COPPER(II) COMPLEXES WITH 2,2'-BIPYRIDINE AND N-TOSYL-SUBSTITUTED AMINO-ACIDS WERE INVESTIGATED THROUGH POLAROGRAPHIC AND PH-METRIC METHOD
VERSATILE BEHAVIOR OF THE CYCLOHEXANE-1,2-DIONE BIS(SEMICARBAZONE) LIGAND IN MONONUCLEAR AND DINUCLEAR METAL-COMPLEXES
No full textThe chelating properties of cyclohexane-1,2-dione bis(semicarbazone) (H-2chds) were considered by means of IR spectroscopy and the crystal structures of [Co2(H-2chds)2(OH2)3(NO3)][NO3]3 1, [Ni(H-2chds)2][NO3]2.2H2O 2 and H-2chds.H2O. The structure of 1 is triclinic, space group P1BAR, with a = 13.616(2), b = 12.694(2), c = 11.537(2) angstrom, alpha = 68.13(1), beta = 63.37(1), gamma = 70.01(1)-degrees, Z = 2 and R = 0.0778. The crystals of 2 are also triclinic, space group P1BAR, a = 13.504(4), b = 13.221(5), c = 8.333(5) angstrom; alpha = 98.00(3), beta = 77.71(4), gamma = 106.43(3)-degrees, Z = 2 and R = 0.0688. The H-2chds.H2O molecule crystallizes in the space group P2(1)/c with a = 7.350(1), b = 15.469(3), c = 10.270(3) angstrom; beta = 93.98(2)-degrees, Z = 4 and R = 0.0372. The behaviour of the ligand is different in each structure: in 1 nearly planar tetradentate and accommodated in the equatorial positions of pentagonal bipyramids; in 2 distorted-octahedral co-ordination is provided by two tridentate ligand molecules having one urea group free. The free molecule is nearly planar with a different conformation: its arms are folded in such a way that an intramolecular N-H ... O hydrogen bond is allowed. The structure of 1 is quite original: dimers are formed by means of two carbonylic bridges; the apices of the two polyhedra are occupied by two water molecules and a nitrate ion and one water molecule respectively
- …
