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Abstract: Cu(II) complexes of the tridentate thiosemicarbazone ligands diacetyl monooxime thiosemicarbazone (dmoTSCH2 ) and diacetyl monooxime (4-phenyl)thiosemicarbazone (dmoPhTSCH2 ) have been synthesized. X-ray crystal structures of dmoPhTSCH2 and [Cu(dmoTSCH)Cl]2 ·H2O (1·H2O) are also reported. The Cu(II) compound 1·H2O is a dinuclear complex, where the Cu(II) centers have a square pyramidal geometry and are bridged by two thiolato ligands. A C2 axis passes through the middle of Cu2S2 rectangle. Variable temperature susceptibility measurement for 1·H2O shows that this compound exhibits a very weak antiferromagnetic behavior (in the solid state) with J 1 = −2.97cm−1, using the Heisenberg isotropic spin Hamiltonian (H =−J 1 S 1·S 2). DFT calculations show that the intramolecular magnetic interaction should be ferromagnetic, and the net antiferromagnetic behavior is due to competition with antiferromagnetic intermolecular interactions through hydrogen bonds. [Copyright &y& Elsevier]

Abstract: The dodecanuclear rhenium anionic complex with terminal hydroxo ligands [Re12CS17(OH)6]6− was obtained by the reaction of K6[Re12CS17(CN)6]·20H2O with molten KOH at 300°C. The cluster complex was crystallized as a potassium salt from aqueous solution. The reaction between K6[Re12CS17(OH)6]·4H2O and Na2S2O4 in water under reflux results in the formation of the complex Na12[Re12CS17(SO3)6]·48.5H2O. Both new compounds were characterized by single-crystal X-ray diffraction, elemental analyses and IR spectroscopy. The electronic structure of [Re12CS17(OH)6]6− was also elucidated by DFT calculations. [ABSTRACT FROM AUTHOR]

Abstract: Mononuclear transition metal complexes of the polyether ionophorous antibiotic monensin (monensic acid, MonH) with nickel(II) and zinc(II) were prepared and characterized using single crystal X-ray diffraction and spectral methods. Monensin complexes crystallize as [Ni(Mon)2(H2O)2]·H2O·5MeCN (1) and [Zn(Mon)2(H2O)2]·H2O·4.5MeCN (2), respectively, in the monoclinic space group P21. Compounds 1 and 2 consist of two monoanionic monensic acid ligands (monensinates) bound in a bidentate coordination mode to the transition metal ion. The metal center is placed in an octahedral environment with monensin anions occupying the equatorial plane of complexes via oxygens of carboxylate and hydroxyl groups located at the both ends of ionophore molecule. The strongly folded antibiotic anions are supported by intramolecular H-bonds, most of them originating from the two aqua ligands attached to the metal(II) ions in axial positions and completing their 6-fold coordination. The bioactivity assay reveals that the presence of divalent metal ion in the monensin complexes influences the biological properties of the ligand and should be taken into account when discussing its mode of action. [Copyright &y& Elsevier]

The novel 3-phenylpyridinium hydrogensquarate (1) has been synthesized and its structure and properties are elucidated spectroscopically, thermally and structurally, using single crystal X-ray diffraction, linear-polarized solid-state IR-spectroscopy, UV-spectroscopy, TGA, DSC, DTA and ESI MS. Quantum chemical calculations were used to obtain the electronic structure, vibrational data and electronic spectrum. 3-Phenylpyridinium hydrogensquarate, crystallizes in the space group P−1 and the ions in the unit cell are joined into layers by intermolecular NH⋯O＝C(Sq) bonds with bond lengths of 2.625 and 2.626 Å, respectively. Hydrogentartarates form dimers by strong O＝COH⋯OCO interactions (2.499 Å). [Copyright &y& Elsevier]

Abstract: The preparation and structural characterization of a new copper(II) complex of the polyether ionophorous antibiotic sodium monensin A (MonNa) are described. Sodium monensin A binds Cu(II) to produce a heterometallic complex of composition [Cu(MonNa)2Cl2]·H2O, 1. The crystallographic data of 1 show that the complex crystallizes in monoclinic space group C2 with Cu(II) ion adopting a distorted square–planar geometry. Copper(II) coordinates two anionic sodium monensin ligands and two chloride anions producing a neutral compound. The sodium ion remains in the inner cavity of the ligand retaining its sixfold coordination with oxygen atoms. Replacement of crystallization water by acetonitrile is observed in the crystal structure of the complex 1. Copper(I) salt of the methyl ester of MonNa, 2, was identified by X-ray crystallography as a side product of the reaction of MonNa with Cu(II). Compound 2, [Me–MonNa][H–MonNa][CuCl2]Cl, crystallizes in monoclinic space group C2 with the same coordination pattern of the sodium cation but contains a chlorocuprate(I) counter [CuCl2]−, which is linear and not coordinated by sodium monensin A. The antibacterial and antioxidant properties as two independent activities of 1 were studied. Compound 1 is effective against aerobic Gram(+)-microorganisms Bacillus subtilis, Bacillus mycoides and Sarcina lutea. Complex 1 shows SOD-like activity comparable with that of the copper(II) ion. [Copyright &y& Elsevier]

Abstract: Two novel l-lysinium hydrogensquarate monohydrate (1) and the corresponding salt of the l-lysinium dication (2) are synthesized and their structure and properties elucidated in detail spectroscopically, thermally and structurally, using single crystal X-ray diffraction, linear-polarized solid-state IR-spectroscopy oriented colloid suspensions in nematic host, TGA, DSC, DTA methods, positive and negative HPLC tandem mass spectrometry (ESI-MS·MS). Quantum chemical methods are used to calculate the electronic structure, vibrational data and electronic spectra. Two novel structural motifs have been obtained, isolated [(HSq−)] and tetramolecular [(H2Sq)(HSq)2(Sq)]4− anion, respectively. Preliminary second harmonic generation measurements are also performed. [Copyright &y& Elsevier]

Abstract: A distortion of the aromatic character and stabilization of the imino-form as a result of the protonation of 4-dimethylaminopyridine was established by IR-, UV- and 1H NMR-spectral analysis of 4-diaminopyridinium hydrogensquarate. Quantum chemical calculations were carried out at MP2 and B3LYP levels of theory and a 6-311++G** basis set with a view to determining the changes in geometrical parameters and IR-spectroscopic characteristics resulting from Npy protonation. Linear-dichroic IR-spectroscopy coupled with the orientation techniques of solid samples as liquid crystal suspensions and melted solid polycrystalline films was applied for the identification of the IR-bands, characteristic for the structural fragments of the neutral and imino-form of the pyridine derivative. The spectral results were compared with the structure, obtained by a single crystal X-ray analysis. The salt contains dimmers of hydrogensquarate anions and Npy protonated cations of which the former are stabilized by strong intermolecular OH…O interactions (2.552Å and 143.1(2)°). The 4-diaminopyridinium cation interacts with the anion through moderate NH…O bonds (2.729Å and 165.0(0)°). Individual cations are π–π stacked with their neighbors at a distance of 3.406Å. [Copyright &y& Elsevier]

Abstract: The title compound was synthesized and characterized by single crystal X-ray diffraction and solid-state polarized IR-spectroscopy of oriented colloids in a nematic host. The compound crystallizes in the monoclinic space group P21/c and its structure consists of a 3D supramolecular network of tyrammonium cations, water and sulfate anions directed by intermolecular hydrogen bonding interactions. Two non-equivalent tyrammonium cations are observed with pseudo T and T trans configurations, respectively. The vibrational characteristics of the non-equivalent molecules are assigned using solid-state polarized IR-spectroscopy. The structural and spectroscopic data are compared with theoretical calculations at the MP2/6-31++G∗ level of theory and basis set using the tyrammonium cation heptahydrate as a model system. [Copyright &y& Elsevier]

Abstract: The novel 3,4-diaminopyridinium hydrogentartarate dihydrate has been synthesized and its structure and properties elucidated in detail spectroscopically, thermally and structurally, using single crystal X-ray diffraction, linear-polarized solid state IR-spectroscopy, UV-spectroscopy, TGA, DSC, DTA and positive and negative ESI-MS. Quantum chemical calculations were used to obtain the electronic structure, vibrational data and electronic spectra. The studied compound crystallizes in the noncentrosymmetric space group P2 1 2 1 2 1 and exhibits a 3D network with molecules linked with participation of cations, anions and solvent molecules. Hydrogentartarates form infinite chains through strong O6;OCO interaction. The effects of N1 protonation on the optical and magnetic properties of 3,4-diaminopyridine are elucidated by comparison with the data of the neutral form. [Copyright &y& Elsevier]

Abstract: Benzamidinium d-glucuronate (1) crystallizes in the orthorhombic space group P212121 and exhibits a 3D network with molecules linked by moderate intermolecular hydrogen bonds (HNH…O(solvent) 2.993Å, HNH…OCO 2.894Å, HNH…O(cycle) 2.844Å, OH…NH2 2.931Å, OH…O(solvent) 2.894, 2.924 and 2.715Å (stronger)) with participation of cations, anions and solvent molecules. The IR-band assignment of carbohydrate moieties is elucidated by a comparison between the types and bond lengths of intermolecular interactions with participation of OH groups in d-glucuronate and linear polarized IR-(IR-LD) spectroscopic data. Experimental results are supported by theoretical ab initio calculations of benzamidinium cation and d-glucuronate anion. [Copyright &y& Elsevier]

Abstract: A cyano-bridged hetero-trinuclear complex, [Cu(HL)]2[Ni(CN)4] (2) (H2L=3,9-dimethyl-4,8-diazaundec-3,8-diene-2,10-dione-dioxime) has been synthesized and characterized by single crystal X-ray structure determination. The square planar [Cu(HL)]+ cation (1), otherwise reluctant to bind axially, is converted to a square pyramidal geometry through axial ligation by the cyano group of [Ni(CN)4]2− ion in di-trans fashion. Electrochemical studies in MeCN give (i) E 1/2(CuII/I)=−0.52V and −0.55V and (ii) E 1/2(CuIII/II)=1.15 and 1.23V versus Ag/AgCl for complexes 1 and 2 respectively, whereas in aqueous solution, the corresponding E 1/2(CuII/I) appear at −0.61V and −0.58V. The E 1/2(CuIII/CuII) appears at 1.04V for 2 only; no such process is encountered for the complex 1 at potential ⩽1.20V. In addition to these there is a redox process, occurring in aqueous solution only, for the copper(II) bound ligand oxidation at 0.63 and 0.60V versus Ag/AgCl for the complex 1 and 2 respectively. Both the complexes undergo acid catalyzed decomposition with a second-order dependence in H+. It is found that complex 2 decomposes at a rate ∼2 times faster than the complex 1. The kinetic studies on the periodate oxidation reveal that both HIO4 and are reacting species for the oxidation of 1, while HIO4 is the sole reacting species for the complex 2. Again, complex 2 reacts faster than 1. An inner-sphere mechanism has been invoked for both the complexes based on large Q, the association constant values. [Copyright &y& Elsevier]