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Tetrazolyl hydrazones of salicylic aldehyde and 2- N-tosylaminobenzaldehyde as well as zinc(II) and copper(II) complexes on their base have been prepared. Quantum-chemical simulation of tautomerism of the hydrazones in vacuum and in the solutions has been performed. IR and NMR spectroscopy and magnetochemistry studies have revealed that the complexes are mononuclear; however, weak intermolecular exchange interaction of the antiferromagnetic type has been detected in the copper(II) complexes. [ABSTRACT FROM AUTHOR]

The binuclear copper(II) complex based on azomethine, being a condensation product of 2-aminoethanol with 1-phenyl-1,2,3-butanetrione phenylhydrazone, is structurally characterized (CIF file CCDC 1059996). The structure is compared with the structure of an analog containing the axially coordinated pyridine molecule. The influence of the axial coordination of pyridine on the magnetic exchange interaction is studied by the DFT method in the broken symmetry approach. [ABSTRACT FROM AUTHOR]

The binuclear copper(II) complex [Cu(L)(Mp)(HO)((CH)SO)] (Mp is 6-methoxypurinate anion) with the heterocyclic azomethine ligand, which is the condensation product of 1,3-diaminopropan-2-ol and 4-hydroxy-3-formylcoumarin (HL), is synthesized and structurally characterized (CIF file CCDC no. 982199). The temperature dependence of the magnetic susceptibility is measured and shows a significant exchange interaction of the antiferromagnetic type (2 J = −348 cm) in the compound. This sharply distinguishes the new complex from the earlier studied compounds with a similar exchange fragment characteristic of the ferromagnetic exchange. The antiferromagnetic exchange parameter is calculated by the quantum-chemical DFT method in the broken symmetry approximation. [ABSTRACT FROM AUTHOR]

Binuclear complexes of copper(II) with 1′-phthalazinylhydrazones of substituted salicylic aldehydes have been prepared and studied. Antiferromagnetic exchange interaction between copper(II) ions has been revealed in all the complexes. Taking advantage of quantum-chemical simulation, we have investigated the influence of the complexes structural isomerism on the character of the exchange interaction between the paramagnetic centers. X-ray absorbance spectroscopy afforded the structural parameters of coordination spheres of copper(II) ions; it has been demonstrated that dimerization occurred via the nitrogen atoms of phthalazine fragments. [ABSTRACT FROM AUTHOR]

The binuclear copper(II) complex [CuL(CHCOO)] ( I), where L is the azomethine trianion based on 3-methyl-4-formyl-1-phenylpyrazol-5-one and 1,3-diaminopropan-2-ol, and its DMSO adduct ( II) in which the DMSO molecule acts as an additional bridging ligand are synthesized. The structure of complex II is determined by X-ray diffraction analysis, and the structure parameters of the coordination unit of complex I are determined by EXAFS spectroscopy. The μ-coordination of the DMSO molecule in compound II results in a change in the sign of the exchange interaction parameter. In complex I, the antiferromagnetic exchange interaction (2 J = −169 cm) occurs between the copper(II) ions. The exchange interaction of the ferromagnetic type (2 J = 174 cm) is observed in complex II. The quantum-chemical calculations of the magnetic exchange parameters by the density functional theory method show that the role of the DMSO molecule as a switch of the exchange interaction character is exclusively the stabilization of the 'broken' conformation of the metallocycles. [ABSTRACT FROM AUTHOR]

Binuclear Cu and Ni complexes with exogenous acetate and pyrazolate bridges were synthesized and studied. It was shown that the μ-coordination of the DMSO molecule in an acetate-bridged Cu complex leads to the inversion of the sign of the exchange interaction parameter. Quantum chemical calculations of the geometry of the complexes and the magnetic exchange parameters showed that the role of the DMSO molecule is to stabilize the 'distorted' conformation of metallocycles. [ABSTRACT FROM AUTHOR]

A tetranuclear copper(II) complex based on azomethine, which is the condensation product of 1-phenyl-3-methyl-4-formylpyrazol-5-one with 1,3-diaminopropan-2-ol, is synthesized. The complex includes two different tetranuclear clusters: symmetrical and unsymmetrical. They have a pseudo-cubane structure and are in a ratio of 1 : 2. The quantum-chemical calculation shows that the 'unsymmetrical' conformer does not correspond to the local minimum on the molecular potential energy surface. Its existence is thus determined by the crystalline packing effects. According to the results of measurements of the temperature dependence of the magnetic susceptibility, the ground spin state is a singlet caused by the overall antiferromagnetic interaction between the copper ions. Accepting the molar magnetic susceptibility of the complex to be equal to the sum of susceptibilities of the 'symmetrical' and 'unsymmetrical' clusters and assuming that the spin-Hamiltonian for both clusters includes three exchange parameters, the temperature dependence of the magnetic susceptibility of the complex is satisfactorily described with the following parameters of the model: J = −178, J = 80, J = 18, J = −26, J = −74, J = 46 cm, g = g = 2.05. [ABSTRACT FROM AUTHOR]

4-Formyl-3-methyl-1-phenylpyrazol-5-one quinolin-2-yl-(H 2L 1) and benzothiazol-2-ylhydrazones (H 2L 2) were synthesized and studied. Quantum-chemical modeling of possible tautomers of the hydrazones was performed. Copper(II) complexes of the general formula [Cu(HL)(ROH)]Y (R = CH 3, C 2H 5; Y=NO 3, ClO 4) were obtained and examined by IR and EPR spectroscopy, magnetochemistry, and X-ray diffraction. Additional coordination through the N atom of the pyrazole ring enables the complex molecules to form zigzag polymer chains linked by intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

Mononuclear copper(II) and nickel(II) complexes with 1,3-bis(3,5-di- tert-butylsalicylideneamino)propan-2-ol (HL) of the general formula [M(HL)] were obtained and structurally characterized. It was demonstrated that the presence of the tert-butyl groups precludes intermolecular hydrogen bonding in the crystals of the complexes and that their molecules are only linked by hydrophobic interactions. [ABSTRACT FROM AUTHOR]

The binuclear copper(II) complex with 2,6-diformyl-4- tert-butylphenol bis(imidazolinylhydrazone) (HL), [Cu(HL)Br]ClO ( I), was synthesized. The structure of complex I was determined by X-ray diffraction analysis. The antiferromagnetic exchange interaction (2 J = −108 cm) translated through the phenoxide oxygen atom is observed between the copper(II) ions. The exchange parameter was calculated by the quantum-chemical 'broken symmetry' method. [ABSTRACT FROM AUTHOR]

From 3-allyl salicylaldehyde and 4-aminoazobenzene (HL), the Schiff-base complex of copper(II) is synthesized and structurally characterized. The crystallographic unit of a CuL ( 1) single crystal contains two independent molecules of the complex. Coordination polyhedra of copper atoms are slightly distorted squares; azomethine ligands are in the trans-position. The neighboring molecules of the complex are bonded by intermolecular π stacking interactions. [ABSTRACT FROM AUTHOR]

1,3-Diaminopropan-2-ol N,N′-bis(3-formyl-5- tert-butylsalicylidene) (HL) and the binuclear copper(II) complex based on HL, [CuL(CHCOO)] ( I), are synthesized. The compounds are studied by IR and H NMR spectroscopies, magnetochemistry, and X-ray diffraction analysis. Compared to the copper(II) complexes with 1,3-diaminopropan-2-ol N,N′-bis(salicylidene), complex I is characterized by a substantial change in the structure resulting in weakening of the antiferromagnetic exchange interaction. [ABSTRACT FROM AUTHOR]

Binuclear copper(II), oxovanadium(IV), and iron(III) complexes with bis-1′-phthalazinylhydrazone of 2,6-diformyl-4- tert-butylphenol have been prepared. An antiferromegnetic exchange interaction between the paramagnetic centers was found. Redox properties of the complexes were studied by the methods of cyclic and differential pulse voltammetry; the reduction of Cu(II) complexes was shown to proceed in two consecutive one-electron steps. [ABSTRACT FROM AUTHOR]

Acid-base properties of hydrazones derived from 8-hydrazinoquinoline and substituted salicylaldehydes were studied. Under the experimental conditions, only the first step of ionization of the hydrazones is realized. The ionization constants were calculated quantum-chemically. Copper(II) complexes of these hydrazones, (HL)Cu(X)(CH3OH)n, were isolated (HL− is the monodeprotonated form of hydrazones, and X− is the acid residue). According to the data of elemental analysis, IR spectroscopy, conductometry, and magnetochemistry, the majority of the complexes have a binuclear structure. The copper(II) ions in the dimeric complex show antiferromagnetic exchange coupling. The ionization constants of the hydrazones and the exchange parameters strongly depend on the substituent in the salicylaldehyde moiety. [ABSTRACT FROM AUTHOR]

The mechanism of thiophene hydrodesulfurization over sulfide catalysts for hydrotreating and the effect of the catalyst composition and feed on the number, distribution, and performance of active sites were studied using 35S and 3H isotopes. Based on the results of radioisotopic study, a method for systematic testing–monitoring of sulfide Co(Ni)Mo catalysts for hydrotreating is developed. The method involves the evaluation of the fraction of the active phase surface occupied by SH groups and the ratio between the concentrations of the surface SH groups and coordinatively unsaturated sites including functioning vacancies. General conditions for the formation and functioning of active sites are formulated on the basis of the monitoring data. Criteria for evaluation of the catalyst performance under conditions of hydrodesulfurization of various kinds of crude are proposed. The results of the pilot tests of commercial catalysts suggest that the criteria proposed are suitable. [ABSTRACT FROM AUTHOR]