Browsing by Author "Dragancea, Diana"

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    CRYSTAL STRUCTURE AND NMR SPECTROSCOPIC CHARACTERIZATION OF 1,5-BIS(2-HYDROXY-3- METHOXYBENZYLIDENE)CARBONOHYDRAZIDE
    (2023) Talmaci, Natalia; Dragancea, Diana; Gorincioi, Elena; Bourosh, Pavlina; Kravtsov, Victor
    The solid-state structure of a symmetrical carbohydrazone, namely 1,5-bis(2-hydroxy-3- methoxybenzylidene)carbonohydrazide was determined by X-ray single crystal diffraction method. Compound 1 crystallizes in the monoclinic space group P21/n with unit cell parameters a= 10.1198(6), b= 22.7847(11), c= 15.1738(10) Å, β= 100.458(6)°, Z= 4, V= 3440.6(3) Å3, R1= 0.0540. Crystal structure of 1 is defined by two crystallographic independent molecules, which are bonded via N–H···O hydrogen bond. The organic molecules are as keto tautomers with respect to the carbamide fragment, and adopt the anti conformation. 1D and 2D NMR experiments have argued on the presence of the title compound in DMSO-d6 solution mostly as keto tautomer in syn conformation, and enol-imino form when considering o-vanillin residue.
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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.