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L. D. Popov Yu. P. Tupolova S. I. Levchenkov V. V. Lukov V. A. Kogan 《Russian Journal of Coordination Chemistry》2007,33(3):208-212
A series of novel mono-and binuclear copper(II) complexes with substituted salicylaldehyde acylhydrazones H2L of the formula CuL · xH2O (x = 0 and 1) and [Cu(HL)](ClO4)(CH3OH) were synthesized. The isolated dimeric complexes of copper acetate were found to exist as isomers with different bridging atoms. In dimers showing a superexchange between the paramagnetic centers through bridging phenoxide O atoms, the antiferromagnetic exchange couplings were much stronger than those in complexes with bridging O atoms of the a-oxyazine fragment. 相似文献
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L. D. Popov S. I. Levchenkov I. N. Shcherbakov V. V. Minin G. G. Aleksandrov E. A. Ugolkova V. V. Lukov V. A. Kogan 《Russian Journal of Coordination Chemistry》2013,39(12):849-856
4-Formyl-3-methyl-1-phenylpyrazol-5-one quinolin-2-yl-(H2L1) and benzothiazol-2-ylhydrazones (H2L2) 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 = CH3, C2H5; Y=NO3, ClO4) 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. 相似文献
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S. I. Levchenkov L. D. Popov I. N. Shcherbakov V. G. Vlasenko A. A. Tsaturyan S. S. Beloborodov A. M. Ionov V. A. Kogan 《Russian Journal of General Chemistry》2014,84(10):1970-1978
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. 相似文献
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A. I. Uraev L. D. Popov S. I. Levchenkov I. N. Shcherbakov V. G. Vlasenko K. Yu. Suponitskii S. S. Beloborodov D. A. Garnovskii V. A. Kogan 《Russian Journal of Coordination Chemistry》2014,40(9):599-606
The copper(II) and nickel(II) complexes based on bis(azomethine), which is the condensation product of 1-phenyl-3-methyl-4-formyl-5-mercaptopyrazole with 1,3-diaminopropan-2-ol, are synthesized. Bis-azomethines can form both binuclear and mononuclear complexes in which the hydroxy group is not involved in coordination. The binuclear copper(II) complexes with the acetate and pyrazolate bridges exhibit an antiferromagnetic exchange, which strength is determined by the nature of the bridge (2J = ?154 and ?424 cm?1, respectively). The structure parameters of the coordination spheres of the complexes are determined by X-ray absorption spectroscopy. The structure of the CHCl3 solvate of the binuclear copper(II) complex with the pyrazolate bridge is solved by X-ray diffraction analysis (CIF file CCDC 964655). 相似文献
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Popov L. D. Levchenkov S. I. Shcherbakov I. N. Tupolova Yu. P. Zubenko A. A. Melkozerova I. E. Lukov V. V. Kogan V. A. 《Russian Journal of General Chemistry》2010,80(9):1853-1859
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. 相似文献
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Choice from a Three-Element Set: Some Lessons of the 2000 Presidential Campaign in the United States
We consider the behavior of four choice rules—plurality voting, approval voting, Borda count, and self-consistent choice—when applied to choose the best option from a three-element set. It is assumed that the two main options are preferred by a large majority of the voters, while the third option gets a very small number of votes and influences the election outcome only when the two main options receive a close number of votes. When used to rate the main options, Borda count and self-consistent choice contain terms that allow both for the strength of preferences of the voters and the rating of the main candidates by voters who vote for the third option. In this way, it becomes possible to determine more reliably the winner when plurality voting or approval voting produce close results. 相似文献
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The issue of estimating the voter power in weighted voting systems is considered. We show that the numerical values of the
weighted power index previously introduced by the author can be determined by a simple minimization scheme. The efficiency
of the method is demonstrated by estimating the influentiality of U.S. Congressmen. 相似文献
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Crystal structure of the polycyclic oxidation product of 1′-phthalazinylhydrazone of 2-formylpyrrole
L. D. Popov S. I. Levchenkov I. N. Shcherbakov G. G. Aleksandrov Yu. P. Tupolova V. V. Lukov O. I. Askalepova V. A. Kogan 《Journal of Structural Chemistry》2013,54(3):619-623
Phthalazinylhydrazone of 2-formylpyrrole is synthesized, the values of ionization constants are determined, and quantum chemical calculation of the geometry and total energy of possible tautomers is performed. The structure of the cyclic oxidation product of hydrazone 3-(1H-pyrrolyl-2)-[1,2,4]-triazolo(3,4-a)phthalazine existing in the crystal in the form of dimers linked by two hydrogen bonds is described. 相似文献