Facultatea de Chimie şi Tehnologie Chimică / Faculty of Chemistry and Chemical Technology

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    Synthesis, structure and properties of some 3d-element complexes with 2-[2-(hydroxybenzylidene)-amino]-2-hydoxymethylpropane-1,3-diol [Articol]
    (2004) Țapcov, Victor; Ciumacov, Iurie; Antoșciac, Boris; Bocelli, Gabrielle; Samusi, Nina; Gulea, Aurelian
    2-[2-(Hydroxybenzylidene)-amino]-2-hydoxymethylpropane-1,3-diol (HL) reacts with cobalt, nickel, copper and zinc chlorides, bromides and acetates in water-ethanol solutions and gives MLX·nH2O and ML 2·nH2O complexes (M = Co, Ni, Cu, Zn; X = Cl, Br; n = 0-5). Single crystals of CuLBr were grown, and its crystal structure was determined by X-ray diffraction analysis. The crystals are tetragonal, a = 17.024(2), c = 8.720(2) Å, space group P421c, Z = 8, R 1 = 0.0349. In the structure of this complex, the copper atom coordinates the deprotonated HL molecule. The coordination polyhedron of the central atom is an elongated tetragonal pyramid. Its base is built of the imine nitrogen atom, phenolic and alcoholic oxygen atoms, and bromine atom. The apex of the pyramid is occupied by the bromine atom of the adjacent complex connected with the initial complex by the plane of sliding reflection. Thus, the crystal contains infinite chains of complexes running along the c axis, the complexes being united by both bridging bromine atoms and O-H⋯O hydrogen bonds. The conclusions on the compositions and structures of the remaining compounds were made on the basis of elemental and combined thermal analyses, IR spectroscopy, and magnetic chemistry data. The copper halide complexes were found to have dimeric, and the other metal complexes monomeric, structures. In the synthesized complexes, the azomethine HL can function as a bidentate or tridentate ligand. The thermolysis of the coordination compounds proceeds through the stages of elimination of crystal water molecules (75-90°C) or inner-sphere water molecules (145-155°C) and complete thermal destruction (485-550°C).
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    Synthesis and study of heterometallic Co-Bi compounds based on ethylenediaminetetraacetic acid. Crystal and molecular structures of [Co(DH)2(o-NH2C6H4CH3)2]2[Bi2(μ-Edta)2(H2O)2]• 10H2O (DH 2 is dimethylglyoxime) [Articol]
    (2002) Stăvilă, Vitalie; Gulea, Aurelian; Șova, Sergiu; Gdanec, M.; Simonov, Iurie
    Compounds of the [Co(DH)2A2](BiEdta)·6H 2O type (where DH is the monodeprotonated dimethylglyoxime -ON=C(CH3)-(CH3)C=NOH; A is the o-, m-, or p-toluidine; and Edta is the ethylenediaminetetraacetate(4-) ion) were synthesized and studied. The composition and structures of the complexes were determined from their UV and 1H NMR spectra and from X-ray diffraction data. The isomer [Co(DH)2(o-NH2C 6H4CH3)2]2[Bi 2(μ-Edta)2(H2O)2]·10H 2O was structurally characterized using X-ray diffraction analysis. The crystals are triclinic: a = 12.153(2) Å, b = 12.824(3) Å, c = 16.215(3) Å, α = 67.73(3)°, β = 86.18(3)°, γ = 66.96(3)°, space group P1̄ , ρ(calcd) = 1.719 g/cm3, Z = 4. The structure is composed of complex binuclear [Bi2(μ-Edta) 2(H2O)2]2- anions, [Co(DH) 2(o-NH2C6H4CH3) 2]+ cations, and molecules of crystallization water. The Edta4- anion chelates with the Bi atom in a hexadentate manner (N2O4); the fifth O atom functions as a bridging ligand. The bismuth coordination polyhedron can be regarded as a strongly distorted antiprism. In the octahedral cation, the Co(III) atom coordinates four N atoms of two DH ligands (average Co-N 1.897 Å) and two N atoms of two o-toluidine molecules (Co-N 2.023 Å). Thermolysis of the complexes studied was found to proceed in several successive steps, namely, the deaquation, deamination, and pyrolysis of the ligands.
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    Synthesis and structure of {μ-oxalato-bis[ethylenediaminetetraacetatobismuthato(III)]}pentaamminethio cyanatocobalt(III)dodecahydrate, [Co(NH3)5NCS]2[(Edta)Bi(μ-C2O4)Bi(Edta)] • 12H2O [Articol]
    (2000) Stăvilă, Vitalie; Gdanec, M.; Șova, Sergiu; Simonov, Iurie; Gulea, Aurelian; Vignacourt, Jean-Pierre
    A heterometallic complex of cobalt(III) and bismuth(III), [Co(NH3)5NCS]2[(Edta)Bi(μ-C2O4)Bi(Edta)] · 12H2O, was synthesized and studied by X-ray diffraction analysis. The crystals are monoclinic, a = 12.792(3) Å, b = 9.792(2) Å, c = 22.945(5) Å, β = 92.92(3)°, P(calcd) = 1.970 g/cm3, space group P21/c, Z = 4. The complex has an isle structure composed of [(Edta)Bi(μ-C2O4)Bi(Edta)]4- and [Co(NH3)5NCS]2+ complex ions and molecules of crystallization water. The Edta4- ligand functions as a hexadentate chelating (2N + 40) agent, while the oxalate ion acts as a bridging ligand. The thiocyanate ion is coordinated to cobalt(III) through the N atom, while the cation interacts with the anion via the Bi-S contact (3.571 Å). Hence, the coordination polyhedron of Bi can be regarded as a tricapped trigonal prism. It was shown that thermolysis of the complex proceeds in several stages, viz., the deaquation, deamination, and pyrolysis of its ligands.
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    Crystal structures of nitrato-{2-[2-(1-pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazolo}aquacopper and chloro-{2-[2-phenyl(pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazolo}copper [Articol]
    (2015) Ciumacov, Iurie; Paholnițcaia, Anastasia; Petrenko, Peter A.; Țapcov, Victor; Poirier, Donald; Gulea, Aurelian
    Two crystal modifications of nitrato-{2-[2-(1-pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazolo}aquacopper (I and II) and two modifications of chloro-{2-[2-phenyl(pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazolo}copper (III and IV) have been synthesized and studied by X-ray diffraction. In structures I and II, the copper atoms coordinate a monodeprotonated molecule of the organic ligand, nitrate ions, and a water molecule. In crystals of I, the complexes are monomeric, whereas complexes II are linked via nitrate ions to form polymeric chains. In both structures the coordination polyhedron of the copper atom can be described as a distorted tetragonal bipyramid—(4 + 1 + 1) in I and (4 + 2) in II. These coordination polyherdra have different compositions. In structures III and IV, the metal atoms coordinate a monodeprotonated {2-[2-phenyl(pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazole molecule and chloride ions. In III the complex-forming ion has square-planar coordination geometry, whereas structure IV consists of centrosymmetric dimers with two bridging chlorine atoms. It was found that nitrato-{2-[2-(1-pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazolo}aquacopper possesses antitumor activity.