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

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    CRYSTAL STRUCTURE OF COPPER SULFATE AND THIOCYANATE COMPLEXES WITH 5-BROMO-AND 5-NITROSALICYLALDEHYDE THIOSEMICARBAZONES
    (2008) Ciumacov, Iurie; Jeanneau, Erwann; Bejenari, Natalia; Țapcov, Victor; Gulea, Aurelian
    The crystal structures of (5-bromosalicylidenethiosemicarbazido) aquacopper(II) sulfato(5-bromosalicylidenethiosemicarbazido)aquacuprate(II) tetrahydrate (I), (5-nitrosalicylidenethiosemicarbazido) dimethylsulfoxide(methanol)copper(II) sulfate (II), and catena(μ-thiocyanato) (5-nitrosalicylidenethiosemicarbazido)copper(II) (III) were determined. In structure I, the independent part of the unit cell contains four water molecules of crystallization and the cation-anion complex [Cu(H2O)(L)] [Cu(H2O)(L)(SO4)] containing two nonequivalent copper complexes (A and B). In these, the metal atom coordinates monodeprotonated 5-bromosalicylaldehyde thiosemicarbazone (HL) and water molecules, and in anion B also a sulfate ion. In complex ions A and B, sulfur, azomethine nitrogen, and phenolic oxygen of the salicylidene thiosemicarbazone fragment, and also water molecule form a distorted planar square around the metal atom. The axial vertex of the pyramid in anion B is occupied by the oxygen atom of the monodentate sulfate anion. In structure II, the independent part of the unit cell contains the (5-nitrosalicylidenethiosemicarbazido)dimethylsulfoxide(methanol)copper(II) complex cation and the sulfate anion. The coordination polyhedron of the central atom is a slightly distorted tetragonal pyramid whose base is formed by sulfur, azomethine nitrogen, phenolic oxygen of thiosemicarbazone, and dimethyl sulfoxide oxygen. The axial position is occupied by the methanol oxygen atom. In structure III, the copper atom coordinates 5-nitrosalicylaldehyde thiosemicarbazone and the thiocyanate ion, which combines complexes into infinite polymer chains along the [010] direction. The copper coordination polyhedron in III is a slightly distorted tetragonal pyramid whose base is formed by sulfur, azomethine nitrogen, phenolic oxygen of thiosemicarbazone, and nitrogen of thiocyanate ion, the axial vertex is occupied by sulfur of thiocyanate ion of the neighboring complex.
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    CRYSTAL STRUCTURE OF 4,4-BIPYRIDINE-CONTAINING COMPLEXES OF COPPER(II) NITRATE WITH 1-[(2-HYDROXYETHYLIMINO)METHYL]NAPHTHALEN-2-OL AND 2-[(2-HYDROXYETHYLIMINO)METHYL]PHENOL
    (2009) Ciumacov, Iurie; Țapcov, Victor; Petrenko, Peter A.; Popovschi, Liliana; Simonov, Iurie; Bocelli, Gabrielle; Antoșciac, Boris; Paraschivescu, Andrei; Gulea, Aurelian
    The crystal structures of (μ-4,4-bipyridine)-di(nitrato-1-[(2- hydroxyethylimino)methyl]naphthalen-2-olocopper (I) and catena-di(μ-4,4'- bipyridine)di(μ-4,4'-bipyridine)-di(nitrato-2-[2-(hydroxyethylimino) methyl]phenolocopper)diaquacopper(II) nitrate (II) were determined. In the crystal of I, each of the two copper atoms coordinates a singly deprotonated tridentate azomethine molecule, a nitrate ion, and bipyridine, which functions as a bridge between the central atoms. The copper coordination polyhedron is a slightly distorted tetragonal pyramid with the base formed by the imine and bipyridine nitrogen atoms and the phenol and alcohol oxygen atoms. The axial site in the pyramid is occupied by the oxygen atom of the monodentate nitrate groups. In the trinuclear structure II with C2 crystal chemical symmetry, the terminal coordination unit is composed through copper coordination of monodeprotonated 2-[2-(hydroxyethylimino)methyl]phenol, bipyridine, and the nitrate anion. In the crystal, the trinuclear molecules form infinite ribbons along the z axis in which the pyridine molecules perform the bridging function. The central copper atom has an octahedral configuration formed by the nitrogen atoms of four 4,4'-bipyridine molecules and oxygen of two water molecules
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    CRYSTAL STRUCTURE OF MONOPROTONATED NI(II) NITRILOTRIACETATE TETRAHYDRATE
    (2004) Petrenko, Peter A.; Gdaniec, Maria; Simonov, Iurie; Stăvilă, Vitalie; Gulea, Aurelian
    A Ni(II) complex of the composition Ni(HNta)·4H 2O (I) was synthesized. Its structure was found to consist of neutral mononuclear [Ni(HNta)(H 2O) 3] complexes and crystallization water molecules. The Ni atom has octahedral surrounding and is coordinated to tridentate-chelate HNta 2- ligand through the N atom and O atoms of two deprotonated acetate groups and through the O atoms of three water molecules. The structure of I was compared with those of the Zn(HNta)·4H 2O and Co(HNta)·4H 2O complexes isostructural to I. Thermogravimetric method showed that the decomposition of compound I occurs through several successive stages of dehydration, deaquation, decarboxylation, and the formation of inorganic residue.
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    SYNTHESIS AND STRUCTURE OF DI(M-OPHENOXY )-BIS{NITRATO-2-[2- (HYDROXYETHYLIMINO)-METHYL]-PHENOLOIMIDAZOLECOPPER}
    (2004) Ciumacov, Iurie; Antoșciac, Boris; Țapcov, Victor; Bocelli, Gabrielle; Gulea, Aurelian
    The crystal structure of di(μ-O phenoxy)-bisnitrato-2-[2- (hydroxyethylimino)-methyl]-phenoloimid-azolecopper was determined. The crystals are monoclinic: a = 10.222(2) , b = 13.810(3) , c = 10.620(2) , β =103.67(3)°, space group P2 1/n, Z = 2, R = 0.050. The copper atom coordinates the singly deprotonated 2-[2-(hydroxyethylimino)-methyl]-phenol molecule, imidazole, and nitrate ion. The coordination polyhedron of the central atom is an extended tetragonal bipyramid with imine and imidazole nitrogen atoms and phenol and alcohol oxygen atoms lying in its base. One axial vertex of the bipyramid is occupied by the oxygen atom of the nitrato group and the other vertex, by phenol oxygen atom of the neighboring complex joined with the initial complex by the symmetry center. Two bridging phenol oxygen atoms unite the complexes into a centrosymmetrical dimer.
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    SYNTHESIS, STRUCTURE AND PROPERTIES OF SOME 3D-ELEMENT COMPLEXES WITH 2-[2-(HYDROXYBENZYLIDENE)-AMINO]-2-HYDOXYMETHYLPROPANE-1,3-DIOL
    (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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    EVALUAREA, ÎN BAZA P RODUSELOR DE ACTIVAR E ALE OXIGENULUI, A POLUĂRII ŞI A AUTOP URIFICĂRII PRIN PROC ESE REDOX A UNOR APE NATURALE
    (CEP USM, 2020) Bunduchi, Elena; Gladchi, Viorica
    Lucrarea de faţă prezintă rezultate ale supravegherii proceselor de poluare şi autopurificare a unor ape naturale sus ţinute de H 2 O 2 şi radicalii OH, din perioada anului 2019. Obiectele monitorizate au fost fl. Nistru, afluenţii săi r. Răut şi r. Ichel, la gurile de confluenţă cu fluviul, precum şi două lacuri de acumulare amplasate în bazinul hidrografic al fl. Nistru, Ghidighici şi Dănceni. Valorile atestate indică la existenţa unor cantităţi scăzute sau chiar lipsa peroxidului de hidrogen, precum şi la prezenţa unor concentraţii importante de substanţe ce întrerup lanţul de autopurificare cu radicalii OH. Acest fapt demonstrează că a existat un consum constant de produse de activare ale oxigenului în procesele redox ce susţin capacitatea de autopurifi care a apelor naturale monitorizate.