131 research outputs found

    The supramolecular arrangement in the Ni(II) complexes of isothiosemicarbazide

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    The molecules of two complexes [Ni(ITSC)2(H2O)2](tere)·2H2O and [Ni(ITSC)2(NO3)2] (ITSC = S-methylisothiosemicarbazide; tere = terephthalate) tend to associate trough the hydrogen bonding interactions into the characteristic 2D blocks separated by the S-methyl moieties. The different coordination mode of the isothiosemicarbazide comparing to thiosemicarbazide (TSC) prevents the formation of the complementary hydrogen bonds with dicarboxylate important for selfassambly of TSC complexes, however in these ITSC the terephthalate anion has role in connection of the blocks and transformation of the 2D into the 3D supramolecular structure. The similar crystal arrangement is found in two earlier reported complexes of Ni(II) with ITSC.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

    Stability of zirconia sol in the presence of various inorganic electrolytes

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    Zirconia sol was prepared from zirconium oxychloride solutions by forced hydrolysis at 102ºC. The prepared sol consisted of almost spherical, monoclinic, hydrated zirconia particles 61 nm in diameter. The stability of zirconia sol in the presence of various inorganic electrolytes (LiCl, NaCl, KCl, CsCl, KBr, KI, KNO3, and K2SO4) was studied by potentiometric titration method. Dependence of the critical concentration of coagulation (CCC) on the dispersion pH was determined for all studied electrolytes. The critical coagulation concentration values, for all investigated electrolytes, are lower at higher pH. These values for all 1:1 electrolytes are equal in the range of experimental error. For a given pH value, CCCs of K2SO4 are 3-4 orders of magnitude lower than the corresponding values for 1:1 electrolytes. [Projekat Ministarstva nauke republike Srbije, br. III 45012

    Crystal and absolute structure of the aquadichloro(pyridoxal thiosemicarbazone) iron(III) chloride

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    A new Fe(III) complex of pyridoxal thiosemicarbazone (H2L) has been characterized by single-crystal X-ray analysis. The Fe atom in the title complex, [Fe(H2L)Cl2(H2O)]Cl, has a distorted octahedral configuration formed by NSO2Cl2 donor set. Six-membered chelate ring significantly deviates from planar form. The crystal structure is stabilized by weak intermolecular C-H…π interaction directed towards the center of the pyridine ring.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

    Ethylenediammonium aquabis(malonato)oxovanadate(IV)

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    In the anion of the title compound, (C2H10N2)[VO(H2O)(C3H2O4)(2)] or H(2)en[VO(mal)(2)H2O], vanadium(IV) is distorted-octahedrally coordinated by six donor O atoms. The two malonate ligands are situated in the equatorial plane, whereas the oxo and the water ligand occupy axial positions. The apical V=O bond exhibits a strong trans influence. The anion possesses crystallographically imposed C-2 symmetry, with the central V atom, the oxo and the water ligand lying on the twofold axis

    Crystal structure of hexakis(mu(2)-chloro)-mu(4)-oxo-tetrakis((3,5-dimethylpyrazole)copper(II)) ethanol tetrasolvate,Cu4OCl6(C5H8N2)(4)center dot 4C(2)H(5)OH

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    C28H56Cl6Cu4N8O5, triclinic, P (1) over bar (no. 2), a = 8.863(1) angstrom, b = 13.939(8) angstrom, c = 17.06(1) angstrom, alpha = 81.67(5)degrees, beta = 85.68(3)degrees, gamma = 84.91(3)degrees, V = 2073.0 angstrom(3), Z = 2, R-gt(F) = 0.080, wR(ref)(F-2) = 0.194, T = 293 K

    Transition metal complexes with Girard reagents and their hydrazones

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    This is the first review dealing with the coordination chemistry of metal complexes with Girard's reagents and their hydrazones. The short introduction points out to chemical properties and significance of these organic compounds. The next section briefly describes synthetic methods for preparing complexes with Girard's reagents, as well as modes of coordination of these ligands. The last two extensive sections review the preparation, stereochemistry and structural characteristics of metal complexes with Girard's hydrazones, including some newer non-hydrazonic derivatives of Girard's reagents, also.[Acknowledgments. Projekat Ministarstva nauke Republike Srbije, br. 172014

    Bis{N,N,N-trimethyl-2-oxo-2-[2-(2,3,4- trihydroxy­benzyl­idene)hydrazin­yl]ethanaminium} tetra­chlorido­zincate(II) methanol solvate1

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    The asymmetric unit of the title compound, (C12H18N3O4)2[ZnCl4]·CH3OH, consists of two Girard reagent-based cations, a tetra­chlorido­zincate anion and a mol­ecule of methanol as solvate. These components are inter­connected in the crystal structure by an extensive network of O—H⋯O, N—H⋯O, C—H⋯O, O—H⋯N, O—H⋯Cl, N—H⋯Cl and C—H⋯Cl hydrogen bonds. The shortest inter­molecular inter­action is realized between the cation and anion [H⋯Cl = 2.29 (5) Å; O—H⋯Cl = 167 (3)°]. C—H⋯O inter­actions also play a important role in the inter­connection of the cations

    Synthesis and structural characterization of Cd(II) complexes with 2-acetylpyridine-aminoguanidine - a novel coordination mode

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    The structures of the first two complexes with bidentate coordination of aminoguanidine Schiff base, i.e., 2-acetylpyridine-aminoguanidine (L), are reported. The complex of the formula [Cd2Cl6(HL)2] (1) was obtained in the reaction of warm aqueous solutions of chloride salts of Cd(II), Zn(II) and the ligand, while the reaction of cadmium bromide and the ligand in the presence of deprotonating agent as well as ammonium thiocyanate resulted in the formation of the complex in which Schiff base has both the role of the ligand and the counterion, viz., [HL][Cd(HL)(NCS)2XY]·H2O (2), where X is Cl- or Br-, and Y Br- or SCN-. The complexes were characterized by IR spectroscopy, elemental analysis, conductometric measurements and single crystal X-ray diffraction. The unusual bidentate coordination of the Schiff base lead to significant changes in the geometry of this molecule (from almost planar in free form and as a tridentate ligand to twisted as a bidentate ligand). Besides, in complex 1 relatively rare bridging coordination of Cl- in octahedral Cd(II) is found, while the crystal structure of complex 2 exhibits substitutional disorder, and contains four different anions: [Cd(HL)(NCS)2Br(SCN)]- (ca. 61 %), [Cd(HL)(NCS)2Cl(SCN)]- (ca. 35 %), [Cd(HL)(NCS)2Br2]- (ca. 3 %) and [Cd(HL)(NCS)2ClBr]- (ca. 1 %)

    Transition metal complexes with thiosemicarbazide-based ligands. Part 60. Reactions of copper(II) bromide with pyridoxal S-methylisothiosemicarbazone (PLITSC). Crystal structure of [Cu(PLITSC−H)H2O]Br•H2O

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    The synthesis and structural characterization of a square-planar copper(II) complex with pyridoxal S-methylisothiosemicarbazone (PLITSC) of the formula [Cu(PLITSC−H)H2O]Br•H2O (1) as the first Cu(II) complex with monoanionic form of this ligand were described. Complex 1 together with two previously synthesized complexes [Cu(PLITSC)Br2] (2) and [Cu(PLITSC)Br(MeOH)]Br (3) were characterized by elemental analysis, IR and electronic spectra and also by the methods of thermal analysis, conductometry and magnetochemistry. [Projekat Pokrajisnkog sekretarijata za nauku i tehnoloski razvoj Vojvodine i Ministarstva nauke Republike Srbije, br. 172014
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