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

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    HYBRID MATERIALS BUILT FROM Cu(II) AND Ni(II) AMINE COMPLEXES AND OXOMETALLATES
    (Academia de Ştiinţe a Moldovei, 2006) Lampeka, Yaroslaw; Barna A.; Shova, Sergiu; Arion, Vladimir
    Polyoxometallate anions (POM) and composite materials thereon possess promising catalytic, magnetic and other physical properties and are nowadays the subject of numerous investigations. One of the ways to tune their characteristics consists in hybridization them with metal complex cations which are able to form coordination bond(s) with nanosized POM clusters. During our search in this direction we succeeded in preparation and structural characterization of some examples of such hybrid materials based on copper(II) and nickel(II) amine complexes. The crystal structures of two complexes, [Cu(2,3,2-tet)( XO4)]·2H2O (2,3,2-tet=1,9-diamino-3,7-diazanonane; X=Mo, W), were estimated by means of single crystal X-ray diffraction analysis. Despite both compounds are isostructural, the peculiarities of copper(II) - anion interaction are different. While in tungstate complex the anion is coordinated to copper in monodentate manner (Cu-O distance 2.311 Å; the closest Cu-O distance to another metal ion 3.125 Å), in molybdate it plays a bridging function (Cu-O distances 2.392 and 2.812 Å). The interaction of the nickel(II) complex of the macrocyclic melaminederived ligand with dodecatungstate anion in DMSO with subsequent diffusion of methanol vapor results in the formation of ionic compound [Ni(LH)(DMSO)][PW12O40]DMSO ·MeOH·7H2O (see figure). The same reaction but with diffusion of water vapor gives again the ionic complex K[NiL(H2O)2][PW12O40]·2H2O. Peculiarities of the packing and the networks of hydrogen bonds in the lattices of all complexes will be discussed in the presentation.
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    IRON(III) COMPLEXES WITH DITOPIC MACROCYCLES BEARING CROWN-ETHER AND BIS(SALICYLIDENE) ISOTHIOSEMICARBAZIDE MOIETIES
    (2023) Arion, Vladimir; Palamarciuc, Oleg; Șova, Sergiu; Novițchi, Ghenadie; Rapta, Peter
    The main aims of this work were the synthesis and characterization of iron(III) complexes with a ditopic ligand H2L consisting of a bis(salicyl- idene)isothiosemicarbazide moiety with a N2O2 binding site and a crown-ether (O6) moiety. A series of high-spin iron(III) complexes, i.e., [FeIIILClBa(CH3OH)(H2O)0.5(ZnCl4)] (1), [FeIIILCl] (2), [FeIIIL(N3)] (3) and [(FeIIIL)2O] (4), were synthesized. The complexes were characterized by mass spectrometry, IR and UV–Vis spectroscopy, variable temperature (VT) mag- netic susceptibility measurements, Mössbauer spectroscopy, single crystal X-ray diffraction and cyclic voltammetry.
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    SYNTHESIS AND CRYSTAL STRUCTURE OF NEW OCTANUCLEAR COPPER(II) COMPLEX WITH BIS(5-CHLORO-2-HYDROXYBENZALDEHYDE) THIOCARBOHYDRAZONE
    (Academia de Ştiinţe a Moldovei, 2006) Dragancea, Diana; Shova, Sergiu; Arion, Vladimir; Gerbeleu, Nicolae
    The reaction of anhydrous copper(II) sulphate with 1,5-bis(5-chloro-2-hydroxybenzaldehyde) thiocarbohydrazone in dimethylformamide/ethanol (1:10), followed by re-crystallization of the product formed from DMSO, yielded the new octanuclear copper(II) complex. According to X-ray diffraction study the compound crystallizes in the triclinic space group P-1 and has the following composition [Cu8L4(DMSO)8]·8.75DMSO·2.5H2O. Each thiocarbohydrazone ligand adopts the thiol anti configuration providing two tridentate coordination sites, one with NNO, and the other with ONS donor atoms, able to accommodate two copper(II) ions. Thus, six of the seven donor atoms of a fully deprotonated ligand L4- are linked with two metal ions to give a dicopper(II) unit {Cu2L}0. The assembly of four such units into a metallomacrocyclic array takes place by coordination of the seventh donor atom of each {Cu2L} unit to the copper(II) atom of the adjacent unit which resides in the ONS ligand pocket to achieve a square-planar geometry. In the resulting architecture four copper(II) atoms are four-coordinate, with two ligands L4- filling all four coordination positions, while the other four copper(II) centers, each accommodated in an ONN ligand pocket, require additional two DMSO molecules to complete their coordination spheres (Fig. 1).figureFig.1 The structure of Cu8L4(DMSO)n.