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Dakovic M.,Laboratory of General and Inorganic Chemistry | Jaglicic Z.,Institute of Mathematics | Kozlevcar B.,University of Ljubljana | Popovic Z.,Laboratory of General and Inorganic Chemistry
Polyhedron | Year: 2010

Three isonicotinamide (isn) copper(II) complexes with different bridging ligands, azide, thiocyanate and sulfate, have been prepared. The molecular structure of [Cu2(μ-1,1-N3)2(μ-1,3-N3)2(isn)2]n (1) is composed of binuclear species, Cu2(μ-1,1-N3)2(isn)2, inter-connected by additional four azide bridges in the end-to-end mode (1,3). This gives a CuN4N square-pyramidal coordination sphere around each copper(II) ion. A trans mononuclear octahedral coordination sphere CuN4S2 is present in [Cu(μ-N,S-NCS)2(isn)2]n (2), with thiocyanato ligands serving as bridges between the adjacent Cu(isn)2 moieties. The third anionic ligand, i.e. sulfate, in {[Cu(μ-O,O'-SO4)(H2O)(isn)2]·2H2O}n (3) completes the CuO2N2O square-pyramidal coordination sphere, and thus enables bridging between the mononuclear Cu(H2O)(isn)2 moieties. The ligands that bridge the principal building blocks, i.e. binuclear in 1 and mononuclear in 2 and 3, connect the axial ligands with the equatorial positions of the copper(II) coordination spheres in all three cases. A ferromagnetic interaction FM is found for 1, while 2 and 3 are paramagnetic. Therefore, the key structural difference between 1 on one hand, and 2 and 3 on the other, is found in the anionic ligand, serving in 1 also as the intra-binuclear bridge, showing the main path (J1) for the FM interaction. Additionally, the inter-binuclear pathway in 1 gives another contribution (J2) to the whole FM interaction seen herein (J1 = 18.5 cm-1, J2 = 4.9 cm-1). © 2010 Elsevier Ltd. All rights reserved.

Mohammadinasab R.,Islamic Azad University at Tehran | Tabatabaee M.,Islamic Azad University at Yazd | Kukovec B.-M.,Laboratory of General and Inorganic Chemistry | Aghaie H.,Islamic Azad University at Tehran
Inorganica Chimica Acta | Year: 2013

A treatment of benzene-1, 2, 4, 5-tetracarboxylic acid (H4btc) and pyridine-2, 6-dicarboxylic acid (H2pydc) with Ce(NO 3)3·6H2O (in the molar ratio 1:1:2) under hydrothermal conditions led to the formation of a new 1D cerium(III) coordination polymer {[(pydc)2Ce2(μ-H 2btc)(H2O)6]4H2O}n (1). Compound 1 was characterized by infrared spectroscopy, elemental analyses and by X-ray diffraction studies. The polymeric chain of 1 contains cerium(III) ions bridged by H2btc2 ligand. Each H2btc 2 ion is connected to four cerium(III) ions via its two bidentate and bridging carboxylate groups. Cerium(III) ion is nine-coordinated by three oxygen atoms from two different H2btc2 ligands, two oxygen atoms and one nitrogen atom from the tridentate pydc2 ligand and three coordinated water molecules, resulting with a distorted tri-capped trigonal prismatic arrangement. Many hydrogen bonds of the O- H··· O type are also present in the crystal structure of 1 and assemble the polymeric chains and the co-crystallized water molecules into a 3D architecture. The coordination polymer 1 was used for the preparation of the CeO2 nanoparticles. Synthesized CeO2 nanoparticles were characterized by infrared spectroscopy, powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The face-centered cubic structure of CeO2 was determined by PXRD. © 2013 Elsevier B.V. All rights reserved.

Cicak H.,Laboratory of Organic Chemistry | Dakovic M.,Laboratory of General and Inorganic Chemistry | Mihalic Z.,Laboratory of Organic Chemistry | Pavlovic G.,University of Zagreb | And 2 more authors.
Journal of Molecular Structure | Year: 2010

The structures of five 6,7-disubstituted 1,3-benzothiazole (1,3-benzothiazole = bta) derivatives: 6-chloro-7-nitro-bta (3), 6-iodo-7-nitro-bta (5), 6-amino-7-iodo-bta (6), 6-acetylamino-7-iodo-bta (7) and 6-amino-7-bromo-bta (8) are reported and investigated by X-ray crystallography and DFT calculations. The crystal structures of 3 and 5-8 are characterized by: (i) relatively weak C{single bond}H⋯O/N/Br and N{single bond}H⋯O/N/S hydrogen bonds, (ii) C{single bond}Cl⋯O and C{single bond}I⋯O/N halogen bonds and Br⋯Br interactions and (iii) π-π interactions. DFT optimized structures of 3, 5, 6 and 8 are in a good agreement with the corresponding X-ray molecular data. Calculated structure of 7 deviates from the experimental geometry because of more favourable intermolecular hydrogen bonding in crystal phase compared to the weak intramolecular hydrogen bond in the gas phase. The molecular electrostatic potential maps were used for predicting possible hydrogen and halogen bonding sites in structures of 3, 5, 6 and 8, and AIM analysis in order to characterize the nature and strength of intermolecular interactions in all of the examined crystal structures. Experimental results agree well with AIM analysis suggesting that the detected hydrogen and halogen bonds are weak and mostly of electrostatic origin. © 2010 Elsevier B.V. All rights reserved.

Kukovec B.-M.,Laboratory of General and Inorganic Chemistry | Kodrin I.,Laboratory of Organic Chemistry | Mihalic Z.,Laboratory of Organic Chemistry | Furic K.,Ruder Boskovic Institute | Popovic Z.,Laboratory of General and Inorganic Chemistry
Inorganica Chimica Acta | Year: 2010

Pyridine and 4-picoline cobalt(II) complexes with 3-hydroxypicolinic acid, [Co(3-OHpic)2(py)2], (2), and [Co(3-OHpic)2(4-pic)2], (3), were prepared, their molecular and crystal structures were determined by X-ray structure analysis and their thermal stability by TGA/DTA methods. Complex 2 appears only as trans isomer and 3 as cis isomer. Based on DFT calculations, the most significant effect on orientation of (un)substituted ligands around cobalt, i.e. cis-trans isomerism, comes from crystal packing. Theoretical calculations show that exchange of methyl group in pyridine does not affect relative stability of one monomer unit, i.e. cis isomer is for about 1 kcal mol-1 more stable than trans isomer. Hydrogen bonds of the O-H···O type are present only as intramolecular ones in the crystal structures of 2 and 3, while intermolecular C-H···O hydrogen bonds and π-π stacking interactions (π-π interactions present only in 3) assemble molecules in 3D architecture. Interactions between two monomer units in crystal packing could be separated and theoretically investigated to calculate interaction energy. In our case, both non-hypothetical models, i.e. trans isomer of 2 and cis isomer of 3, show more favorable interaction energies than hypothetical ones, i.e. cis isomer of 2 and trans isomer of 3, for the same type of interaction. © 2010 Elsevier B.V. All rights reserved.

Stilinovic V.,Laboratory of General and Inorganic Chemistry | Cincic D.,Laboratory of General and Inorganic Chemistry | Zbacnik M.,Laboratory of General and Inorganic Chemistry | Kaitner B.,Laboratory of General and Inorganic Chemistry
Croatica Chemica Acta | Year: 2012

A Schiff base dicarboxylic acid (1) was prepared by condensation of 2-hydroxy-1-naphthaldehyde with 5-aminoisophthalic acid. Its solvates with pyridine (2a and 2b) and dimethylformamide (3) were prepared by liquid-assisted grinding and by conventional solvent-based methods. All products were characterised by FT-IR spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The structures of 1, 2b and 3 were determined by single crystal X-ray diffraction. 1 was found to be a pure Schiff base, 2b a pyridine solvate and 3 a dimethylformamide solvate monohydrate. In all three structures, the Schiff base molecule appears to be present as the ketoamine tautomer.

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