2. Articole
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Item COORDINATION COMPOUNDS OF COPPER(II) NITRATE WITH PRODUCTS OF AMINOTRIS(HYDROXYMETHYL)METHANE CONDENSATION WITH SALICYL- AND 5-NITROSALICYLALDEHYDES: SYNTHESIS AND CRYSTAL STRUCTURES(2005) Ciumacov, Iurie; Țapcov, Victor; Simonov, Iurie; Antoșciac, Boris; Bocelli, Gabrielle; Perrin, Monique; Starnicova, Zoia; Samusi, Nina; Gulea, AurelianThe crystal structures of copper(II) nitrate complexes with 2-(2-hydroxybenzylideneamino)-2-hydroxymethylpropane-1,3-diol (HL) and 2-hydroxymethyl-2-(2-hydroxy-5-nitrobenzylideneamino)propane-1,3-diol (HL 1) were determined. The resulting complexes were formulated as [Cu3OL3(H2O2]NO3 • 3H2O (I) and [Cu(H2O)L1]NO3 (II). The crystals of I are monoclinic, a = 17.809(4) Å, b = 30.549(6) Å, c = 18.962(4) Å, β = 115.36(3)°, space group Cc, Z = 8, R = 0.0482. Complex I is composed of two independent three-dimensional μ 3-oxo complexes; the coordination polyhedron of the copper atoms in both compounds is an elongated tetragonal bipyramid. The coordination polyhedron of the third Cu atom is a tetragonal pyramid. The bases of the pyramids are composed of the oxygen atoms of the phenol and alcohol OH groups, the imine N atom of ligand L, and μ 3-oxo atoms. The phenol and water O atoms serve as the apices in both the tetragonal bipyramids. The crystals of II are triclinic, a = 6.062(1) Å, b = 7.701(2) Å, c = 16.162(3) ̊, α = 88.15(3)°, β = 84.94(3)°, γ = 78.13(3)°, space group P1̄, Z = 2, R = 0.0272. Complex II is composed of polymer chains formed by coordination bonds between the copper atom and two O atoms of the amino alcohol in the azomethine of the neighboring complex connected to the initial one by translation along the x axis. These chains are linked through hydrogen bonds involving the oxygen atoms of the NO2 groups. The benzene rings of the azomethine ligands of the adjoining complexes from different chains are antiparallel to each other. The coordination polyhedron of the central atom is an elongated tetragonal bipyramid. Its equatorial plane is formed by the phenol O atom, one of the alcohol O atoms, the N atom of ligand L1, and the O atom of the amino alcohol in the neighboring complex. The apices are the O atom of the water molecule and the O atom of the amino alcohol in the neighboring azomethine molecule. In complexes I and II, the outer-sphere nitrato group mainly serves to unite trimers and polymers in the crystal by means of hydrogen bonds.Item NEW CRYSTAL FORMS OF TRIS(2-AMINOETHANOLATO-O,N)COBALT(III): STRUCTURES AND PROPERTIES(2006) Cotovaia, Aliona; Șova, Sergiu; Simonov, Iurie; Roșu, Tudor; Sandu, Ion; Gulea, AurelianCrystal forms of cobalt(III) tris(2-aminoethanolate) hydrates, i.e., red cubic crystals of the composition fac-[Co(NH2CH2CH 2O)3] • 5.44H2O (fac-I • 5.44H 2O) and blue prismatic crystals of the composition mer-[Co(NH 2CH2CH2O)3] • 3H2O (mer-I • 3H2O) were studied by the 59Co, 13C NMR and X-ray diffraction methods. It was found that mer-[Co(NH2CH2CH2O)3] • 3H 2O (mer-I • 3H2O) is a new pseudopolymorphic modification of fac-[Co(NH2CH2CH2O) 3] • 3H2O (fac-I • 3H2O), while fac-I • 3H2O represents a new polymorphic modification of the complex mer-[Co(NH2CH2CH2O)3] • 3H2O (mer-I • 3H2O) described previously. The comparative analysis of the spectra revealed dynamic equilibrium between these geometric isomers; the fac-isomer is stable in aqueous solutions.Item CRYSTAL STRUCTURE OF MONOPROTONATED NI(II) NITRILOTRIACETATE TETRAHYDRATE(2004) Petrenko, Peter A.; Gdaniec, Maria; Simonov, Iurie; Stăvilă, Vitalie; Gulea, AurelianA 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.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, IurieCompounds 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.