Chemistry Journal of Moldova

DOI: dx.doi.org/10.19261/cjm.2010.05(1).10

Graphical Abstract: The dissolution of the iron from steel was observed by drawing the cyclic voltammetry (CV) for the systems consisting of the solution resulted when the alloy sample was immersed in HNO3, H2SO4, and HCl, aqueous solutions on platinum disk electrode (PtDE). The presence of some redox processes can be observed only in HNO3 which confirms the complexity of the mechanism of Fe dissolution in this acid. On the other hand, there were manufactured electrodes of steel samples taken into experiment achieving the corrosion characteristics in the media mentioned above.


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DOI: dx.doi.org/10.19261/cjm.2011.06(2).15

Graphical Abstract: We have researched the color properties of coordination compounds synthesized by us previously [1] (8-(1',2'-naphthyl)-1-
R3-methyl-6-thiomethyl-4,5,7-triazaocta-1,3,5,7-tetraenato-1,1'-diolato(-)O, O', N4, N7-M(II), where R=CH3, C6H5, M=Ni, Co, Cu), which can be used for coloring thermoplastic masses. They meet the requirements for use as a pigment for coloring thermoplastic masses.


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DOI: dx.doi.org/10.19261/cjm.2009.04(2).09

Graphical Abstract: The complexes of general formula MCl₂∙L^1-4∙nH₂O (where L¹ - N-(2,4,7-trinitrofluorenilidene-9)-p-dimethyl-aminoanilin, L² - N-(2,4,5,7-tetranitrofluorenilidene-9)-p-dimethylaminoaniline, L³ - N-(2,4,7-trinitrofluorenilidene)-N-(p-dimethylaminophenyl)hydroxylamine, L⁴ - N-(2,4,5,7-tetranitrofluorenilidene-9)-N-(p-dimethylaminophenyl)-hydroxylamine; M=Cu, Co, Ni, Zn; n= 1-3 have been synthesized and investigated by different methods. Spectral criteria of co-ordination of the molecules L¹ –L⁴ in electronic adsorption spectra were detected.


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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2009.04(2).10

Graphical Abstract: Nine new complexes with the general formula {[Ln₂Ba(α-Fur)₈(H₂O)₄]}_n, where Ln = Nd³⁺, Sm³⁺, Eu³⁺, Pr³⁺, Gd³⁺, Tb³⁺, Ho³⁺, Er³⁺ and La³⁺; α-Fur ≡ C₄H₃OCOO, were synthesized and characterized by IR spectra, magnetism, X-ray single crystal and powder diffractions.


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DOI: dx.doi.org/10.19261/cjm.2009.04(1).06

Graphical Abstract: A chloro-bridged chain complex constructed from paddlewheel-type dinuclear ruthenium(II,III) carboxylate units, [Ru2{3,4,5-(C2H5O)3C6H2CO2}4Cl]n·1.2nC2H5OH (1·1.2nC2H5OH), was synthesized and characterized by elemental analysis and IR and UV-vis spectroscopies. The single-crystal X-ray analysis showed that the complex forms a zig-zag chain structure, in which the chloroligands bridge the dinuclear units at the axial positions with the Ru1–Cl–Ru2 angle of 120.38(7)°. A broad band around 1144 nm and a band at 475 nm were observed in the diffused reflectance spectra and ascribed to a δ→δ* and a π(RuO, Ru2)→π*(Ru2) transitions, respectively. Temperature dependence of magnetic susceptibility showed that the antiferromagnetic interaction between the dinuclear units is weak (zJ = −0.8 cm−1) with D value of 60 cm−1.


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DOI: dx.doi.org/10.19261/cjm.2008.03(2).04

Graphical Abstract: Two novel μ3-oxo-centered carboxylate-bridged triiron complexes [Fe3O(BrCH2COO)6(H2O)3] NO3·2.63H2O (1) and [Fe3O(CH2BrCOO)1.5(CH2ClCOO)4.5(H2O)3]Br0.75Cl0.25 5H2O (2) were synthesized and their structures were characterized by X-ray crystallography. The opportunity of mixed-ligand complex formation in iron(III)-bromoacetic acid system was shown. The first co-ordination sphere of the iron atom in compound 2 includes two different carboxylate anions, CH2BrCOO- and CH2ClCOO- in the capacity of syn-syn- bidentate-bridged ligands, while Br- and Cl- anions being in the ratio 1:1, formulate the external sphere of the complex. The IR spectra, thermic analysis and magnetic properties of complexes were studied.


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DOI: dx.doi.org/10.19261/cjm.2008.03(2).06

Graphical Abstract: A novel hexanuclear iron-calcium-oxo complex has been synthesized and characterized by different physico-chemical methods and X-ray single crystal structural analysis: [Fe4Ca2O2(μ2-HCCl2COO)10(μ3-HCCl2COO)2(THF)6].The molecular structure shows that there are two types of coordination for COO- anions: bidentate and tridentate.The corresponding variable temperature susceptibility measurement shows that in the complex there exists an antiferromagnetic interaction (|J12| = |J34| = -71.86 cm-1). The iron(III) high spin state (5/2) is proved by Mössbauer spectroscopy. High magnetic EPR measurements of 1 indicates the presence of S=0 ground state with low-lying S=1 excited state centred around g = 2.0054 ±0.0001.


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DOI: dx.doi.org/10.19261/cjm.2008.03(2).13

Graphical Abstract: The new ligand, bis(2-hydroxybenzaldehyde)diaminoguanizone (1) has been synthesized and characterized by elemental analysis, IR and 1H NMR spectroscopies. The crystal structure of the compound was determined by X-ray diffraction. The ligand C15H15N5O2·C2H5OH crystallizes in the monoclinic space group P21/c with unit cell parameters a = 8.9102(3), b = 10.0357(3), c = 19.7618(6) Å, β = 98.385(2)°, Z = 4, V = 1748.21(9) Å3, R1 = 0.040. The amino form of the ligand adopts a planar conformation stabilized by two intramolecular hydrogen bonds of the type O–H···N, in which the H atoms of the central amino group are directed to the lone-pair regions of the azomethine nitrogen atoms.


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DOI: dx.doi.org/10.19261/cjm.2008.03(2).15

Graphical Abstract: It was elaborated the methodology of synthesizing a series of new dioximates of Co(III) with the general formula [Co(DioxH)2(L)2]X⋅nH2O, where DioxH – the dioxime anione: dimethylglyoxime (DH2), 1,2-cyclohexanedionedioxime (NioxH2); L - thiocarbamide (Thio), pyridine (Py), aniline (An), sulphanilamide (Sam);X - [BF4]-, [ZrF6]2-, [TiF6]2-, whose structures have been studied with the help of contemporary physical methods: spectroscopy IR, UV-Vis, RMN 1H, 19F, X-ray analysis. There were elaborated optimal conditions of using cobalt dioximates with fluorine in order to intensify the biosynthesis of amylases and lipases by Aspergillus and Rhizopus strains, respectively. The tested compounds increase the lipolytic activity of Rhizopus arrhisus micromycetes.


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DOI: dx.doi.org/10.19261/cjm.2008.03(2).16

Graphical Abstract: This work is devoted to the investigation of the template reactions of organic compounds derived from S-alkylisothiosemicarbazide and β-dicarbonylic compounds (acetyl(benzoyl)acetone, 2,6-diformylpyridine, 2,6-diformyl-4-methylphenol, 1-hydroxy-2-naphthaldehyde, sodium nitromalonic dialdehyde, 1,1,3,3-tetraetoxypropane, 3-ethoxyacroleine) in the presence of 3d-metal ions, determination of the structure and properties of the prepared complexes. There were elaborated original methods for synthesis of open-chain or macrocyclic coordination compounds of nickel(II), copper(II), oxovanadium(IV) and cobalt(II) with N4, N3O and N2O2 tetradentate ligands. Two types of hexaazamacrocyclic systems with trans- and cis- arrangement of thiosemicarbazide fragments have been obtained using template condensation of different precursors. The biostimulative properties (biomass accumulation and increasing of enzymatic activity) of complexes have been established. Some complexes of nickel(II) have been studied as coloring agents for plastics.


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