Chemistry Journal of Moldova

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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DOI: dx.doi.org/10.19261/cjm.2007.02(1).06

Graphical Abstract: Thiolato-bridged complex [Cu^I₄Cu^II₄(peampt)₄Cl₈]·2H₂O (Hpeampt = 1-(2-pyridylethyl)amino) methylpropane-2-thiol) has been synthesized and characterized by the elemental analysis, IR and UV-vis spectroscopies and magnetic susceptibility measurement. The X-ray crystal structure analysis of this complex shows a localized mixed-valence octanuclear cage structure made up of four trigonal-bipyramidal Cu^IIN₂SCl₂, two trigonal CuIS2Cl, and two tetrahedral Cu^IS₂Cl₂ coordination sites. Temperature dependence of magnetic susceptibility (4.5— 300 K) shows that a fairly strong antiferromagnetic interaction is operating between the four Cu^II ions.


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DOI: dx.doi.org/10.19261/cjm.2007.02(1).07

Graphical Abstract: The solid-state structure of the tri-potassium calix[4]arene dihydroxyphosphonate salt is presented. In this structure, two potassium cations bridge between layers of dimeric calixarene diphosphonate units and two other potassium cations bridge along the face of the layers. The ubiquitous dimeric association of the calixarenes shows the highest interdigitation value so far observed. As expected, the cations are solvated and are complexed exo with respect to calixarene crown. The octahedral coordination sphere of the potassium cations is formed by two phosphonate groups of the calixarenes and four water molecules. Electrostatic forces represent the major element of interaction in the solid-state system.


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DOI: dx.doi.org/10.19261/cjm.2007.02(1).08

Graphical Abstract: The interaction of cis-Re₂(RCOO)₂Cl₄, trans-Re₂(RCOO)₂Cl₄, Re₂(RCOO)₃Cl₃ and Re₂(RCOO)₄Cl₂ (where R - alkyl group) with 1,3,5-triphenylverdazyle radical in 1,2-dichlorethane was investigated. It is discovered, that gradual substitution of halogenide ligands by carboxylates in dirhenium(III) clusters led to slowing down of reaction with a radical due to different influence of these ligands on parameters of rhenium - rhenium bond. Presented data showed perspectivity of Re₂⁶⁺-substances applications as therapeutic agents due to their low toxicity and antiradical properties that occured by δ-component of quadruple Re-Re bond electron transition.


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DOI: dx.doi.org/10.19261/cjm.2007.02(1).09

Graphical Abstract: Interactions of a series of indole-3-alkanoic acids (with n-alkanoic acid side-chains from C1 to C4) with iron(III) in acidic aqueous solutions have been shown to comprise two parallel processes including complexation and redox transformations giving iron(II) hexaaquo complexes. The structure and composition of the reaction products are discussed, as analysed using a combination of instrumental techniques including 57Fe Mössbauer, vibrational and HNMR spectroscopies.


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DOI: dx.doi.org/10.19261/cjm.2007.02(1).10

Graphical Abstract: Four new heteronuclear lanthanide complexes with general formula [Ge(OH)(μ-HDTPA)LnGe(OH) (μ-DTPA)] (Ln = Sm – Dy) were synthesized and subsequently characterized by different physico- chemical methods. The structures of new compounds have been proposed. In considered complexes the 4f-luminescence of three-charged ions of samarium, europium, terbium and dysprosium is realized at UV-excitation. It is noteworthy that it is the first observation of 4f-luminescence in water solutions of heteronuclear f-p-complexes. The comparison of luminescent characteristics of hetero- and homonuclear landthanide complexes is described and discussed as well.

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