2. Articole

Permanent URI for this collectionhttps://msuir.usm.md/handle/123456789/46

Browse

Has files: YesSubject: search.filters.subject.cobalt

Search Results

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    EFFECT OF THE NATURE OF THE ANION ON THE COMPOSITION AND STRUCTURE OF COBALT COMPLEX WITH MONOETHANOLAMINE
    (2013) Cotovaia, Aliona; Șova, Sergiu; Melnic, Elena; Simonov, Iurie; Gulea, Aurelian; Pahonțu, Elena
    A number of products formed in reactions of cobalt(II) salts with monoethanolamine (HEtm) in a neutral medium were synthesized and studied. X-Ray diffraction study showed that the nitrate and acetate form the dimers [Co(HEtm)3][Co(Etm)3](NO3)3 and [Co(HEtm)3][Co(Etm)3](CH3COO)3 · 8H2O, respectively. In chloride solutions, cobalt is partially oxidized to give the trinuclear complex [CoII{Co III(Etm)3}2]Cl3 · H 2Etm · 2H2O. The reaction of the chelate [Co(Etm)3] · 3H2O with nitric acid is accompanied by complete protonation of the coordinated aminoethanolate ions, and the reaction with formic acid involves complete replacement of the coordinated ligand by acid residue anions and water molecules to give the coordination polymer {Co2(μ-HCOO)4(H2O)4} n .
  • Thumbnail Image
    Item
    NEW COMPLEXES OF TRIS(2-AMINOETHANOLATO-O,N)COBALT(III) SULFATES: SYNTHESIS AND STRUCTURE
    (2009) Cotovaia, Aliona; Șova, Sergiu; Simonov, Iurie; Gulea, Aurelian
    The reaction of [Co(Etm)3] • 3H2O (I) with sulfuric acid affords [Co(HEtm)3]2(SO4) 3 • 4H2O (II). The change in the synthesis procedure (the direction interaction of cobalt(II) sulfate with β-aminoethanol (HEtm)) makes it possible to isolate [Co(HEtm)3](SO 4)(HSO4) • H2O (III) and {[Co(HEtm) 3][Co(Etm)3]}2(SO4)3 • 7.75H2O (IV). The X-ray diffraction analyses of compounds II-IV show that all of them are of the ionic type. In compounds II and III, the ionic structure consists of the [Co(HEtm)3]3+ cations and sulfate anions in a ratio of 2: 3 and 1: 2, respectively. The basic difference in compounds II and III is the different degrees of deprotonation of the acid residues. In complex II, two anions SO 4 2- are doubly deprotonated. In complex III, of the four anions found in the independent part of the unit cell of the sulfate anion two anions are monodeprotonated. In structure IV, two crystallographically independent complexes [Co(HEtm) 3]3+ and [Co(Etm)3] are joined into a dimer through the O-H⋯O hydrogen bonding.
  • Thumbnail Image
    Item
    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).
  • Thumbnail Image
    Item
    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(M-EDTA)2(H2O)2] • 10H2O (DH2 IS DIMETHYLGLYOXIME)
    (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.
  • Thumbnail Image
    Item
    EFECTUL STIMULATOR AL TRIS - β -AMINOETILAŢILOR DE COBALT(III) ASUPRA PRODUCTIVITĂŢII CIANOBACTERIEI SPIRULINA PLATENSIS
    (CEP USM, 2008) Cotovaia, Aliona; Gulea, Aurelian; Şova, Sergiu; Ciumac, Daniela; Bulmaga, Valentina; Ţurcanu, Ştefan; Rudic, Valeriu
    As a result of cobalt (III) β-aminoethylate protonation reactions with sulfuric and nitr ic acids, several new coordination compounds of composition [Co(Hetm)3](NO3)3(1) and [Co(Hetm)3]2(SO4)3⋅4H2O (2) have been synthesized. The reaction between β -aminoethanol and cobalt(III) nitrate, acetate and sulfate in neutral or slightly basic alcoholic media leads to the formation of cobalt (III) coordination compounds, which internal sphere includes both molecules of neutral β-ami-noethanol (Hetm) and ions of its deprotonated form (etm). The general formula of the complexes can be given as [Co(Hetm)3][Co(etm)3]X3nH2O, where X = NO3- (3), CH3COO- (4), 1/2SO42- (5); n = 0, 7, or 3 correspondingly. The biologic activity study of the synthesized complexes revealed that the algae biomass obtained in the nutritive media, containing coordination compounds, depends on the internal coordination sphere of the cobalt compound.
  • Thumbnail Image
    Item
    SINTEZA DIRIJATĂ A BAZELOR SCHIFF CARE CONŢIN HIDRAZINOBENZOTIAZOL, 4-AMINOTRIAZOL, LIZINĂ ŞI COMPUŞII LOR COORDINATIVI
    (CEP USM, 2016) Paholniţcaia, Anastasia
    Lucrarea prezintă o revistă a bazelor Schiff care conţin hidrazinobenzotiazol, 4-aminotriazol, lizină şi compuşii coordinativi cu aceşti liganzi descrise în literatura de specialitate. Compuşii coordinativi ai elementelor 3d cu aceşti liganzi au deferită compoziţie, structură şi proprietăţi. Liganzii şi compuşii coordinativi manifestă activitate antitumorală, antibacteriană, antituberculoasă, antiinflamatoare. Compuşii coordinativi ai cuprului cu aceşti liganzi manifestă activitate antitumorală sporită în comparaţie cu bazele Schiff corespunzătoare.
  • Thumbnail Image
    Item
    STUDIUL SPECTROFOTOMETRIC AL COMPUŞILOR COORDINATIVI AI COBALTULUI(II), NICHELULUI(II) ŞI CUPRULUI(II) CU TIOSEMICARBAZONA ALDEHIDEI 5-(METILENTRIMETILAMONIU)SALICILICE
    (CEP USM, 2016) Sîrbu, Angela
    Tiosemicarbazona aldehidei 5-(metilentrimetilamoniu)salicilice ([H2L]Cl) are structură ionică, este solubilă în apă şi formează cu ionii de cobalt(II), nichel(II) şi cupru(II) compuşi coloraţi caracterizaţi spestral prin maximum de absorbţie la 390 nm, 373 nm şi 375 nm, respectiv. Raportul molar de combinare metal:ligand este 1:1 pentru cupru şi nichel şi 1:2 pentru cobalt. Prin studiul spectrofotometric au fost determinate condiţiile optime de formare a complecşilor, absorbtivitatea molară şi stabilitatea speciei dominante. În baza studiului realizat a fost propusă o metodă de determinare a conţinutului de cupru şi cobalt cu reactivul ionic nou.