Benzoin (phthalazin-1-yl)hydrazone and its complexes with copper(I), copper(II), and nickel(II) were synthesized. Acid-base properties of benzoin (phthalazin-1-yl)hydrazone were studied, and its ionization constants and energies of possible conformers were calculated by quantum-chemical methods. The structure of the isolated complexes was determined on the basis of their elemental compositions, IR spectra, and data of thermogravimetric, conductometric, and magnetochemical measurements. Copper(II) acetate with benzoin (phthalazin-1-yl)hydrazone forms dinuclear complex, nickel(II) acetate and chloride produce mononuclear octahedral complexes, and copper(II) halides give rise to copper(I) complexes with the oxidized hydrazone.
Structure, tautomeric rearrangements, acid-base properties and complex formation ability of 1-hydrazinophthalazine hydrazones
and their coordination compounds with transition metals are considered. The main factors influencing the structure and physicochemical
properties of the complexes, biological activity of phthalazine hydrazones and their complexes are discussed. 相似文献
Rate constants and activation parameters of two-step azidation of isomeric dicyanobenzenes with dimethylammonium azide in DMF at 70–100°C were determined. Tetrazole rings are formed from cyano groups in dicyanobenzenes in a stepwise mode following the 1,3-dipolar cycloaddition pattern. The rate of azidation of isomeric dicyanobenzenes is considerably higher than the rate of subsequent azidation of intermediate cyanophenyltetrazolides. The azidation rate constant decrease in going from m-dicyanobenzene to its para and ortho isomers. 相似文献
PAls should stick together : The cyclo‐trimer 2 is obtained by H2 elimination of Lewis acid/base‐stabilized parent compound of the phosphanylalanes 1 . The elimination is controlled by fine tuning the temperature and solvent conditions. A subsequent H2 elimination produces the ladder compound 3 . Compounds 2 and 3 are the first of a new class of Group 13/15 compounds which show no additionally donor–acceptor bonds within the framework.
We find the asymptotics as λ/? → ?∞ of the density of the spectral measure of the Sturm-Liouville operator in L2(0,+∞) generated by the expression ?y″ + ?q(x)y, ? > 0, with the boundary condition y(0) cos α+y′(0) sinα = 0. The potential q(x) tends to ?∞ as x → +∞ and is assumed to satisfy the Sears condition and some additional regularity conditions. 相似文献
We consider the weakly singular boundary integral equation on a deterministic smooth closed curve with random loading g(ω). Given the kth order statistical moment of g, the aim is the efficient deterministic computation of the kth order statistical moment of u. We derive a deterministic formulation for the kth statistical moment. It is posed in the tensor product Sobolev space and involves the k-fold tensor product operator . The standard full tensor product Galerkin BEM requires unknowns for the kth moment problem, where N is the number of unknowns needed to discretize Γ. Extending ideas of [V.N. Temlyakov, Approximation of functions with bounded mixed derivative, Proc. Steklov Inst. Math. (1989) vi+121. A translation of Trudy Mat. Inst. Steklov 178 (1986)], we develop the p-Sparse Grid Galerkin BEM to reduce the number of unknowns from to . 相似文献
We give the first known bound for orders of differentiations in differential Nullstellensatz for both partial and ordinary algebraic differential equations. This problem was previously addressed in [A. Seidenberg, An elimination theory for differential algebra, Univ. of California Publ. in Math. III (2) (1956) 31–66] but no complete solution was given. Our result is a complement to the corresponding result in algebraic geometry, which gives a bound on degrees of polynomial coefficients in effective Nullstellensatz [G. Hermann, Die Frage der endlich vielen Schritte in der Theorie der Polynomideale, Math. Ann. 95 (1) (1926) 736–788; E.W. Mayr, A.W. Meyer, The complexity of the word problems for commutative semigroups and polynomial ideals, Adv. Math. 46 (3) (1982) 305–329; W.D. Brownawell, Bounds for the degrees in the Nullstellensatz, Ann. of Math. 126 (3) (1987) 577–591; J. Kollár, Sharp effective Nullstellensatz, J. Amer. Math. Soc. 1 (4) (1988) 963–975; L. Caniglia, A. Galligo, J. Heintz, Some new effectivity bounds in computational geometry, in: Applied Algebra, Algebraic Algorithms and Error-Correcting Codes, Rome, 1988, in: Lecture Notes in Comput. Sci., vol. 357, Springer, Berlin, 1989, pp. 131–151; N. Fitchas, A. Galligo, Nullstellensatz effectif et conjecture de Serre (théorème de Quillen–Suslin) pour le calcul formel, Math. Nachr. 149 (1990) 231–253; T. Krick, L.M. Pardo, M. Sombra, Sharp estimates for the arithmetic Nullstellensatz, Duke Math. J. 109 (3) (2001) 521–598; Z. Jelonek, On the effective Nullstellensatz, Invent. Math. 162 (1) (2005) 1–17; T. Dubé, A combinatorial proof of the effective Nullstellensatz, J. Symbolic Comput. 15 (3) (1993) 277–296].This paper is dedicated to the memory of Eugeny Pankratiev, who was the advisor of the first three authors at Moscow State University. 相似文献
The Toda lattice and the discrete Korteweg-de Vries equation generalized to two dimensions are studied numerically. The interactions are assumed to be identical in both directions. It is shown that the equations have solutions in the form of plane linear and localized solitons. In contrast to equations integrable by the inverse scattering method, the parameters of solitons change in the course of their interaction and additional wave structures are formed. The basic types of solutions characterizing these processes are presented. 相似文献
We studied the role of alkali cations in the [{RuCl2(p-cymene)}2]-pseudo-dipeptide-catalyzed enantioselective transfer hydrogenation of ketones with isopropanol. Lithium salts were shown to increase the enantioselectivity of the reaction when iPrONa or iPrOK was used as the base. Similar transfer-hydrogenation systems that employ chiral amino alcohol or monotosylated diamine ligands are not affected by the addition of lithium salts. These observations have led us to propose that an alternative reaction mechanism operates in pseudo-dipeptide-based systems, in which the alkali cation is an important player in the ligand-assisted hydrogen-transfer step. DFT calculations of the proposed transition-state (TS) models involving different cations (Li+, Na+, and K+) confirm a considerable loosening of the TS with larger cations. This loosening may be responsible for the fewer interactions between the substrate and the catalytic complex, leading to lower enantiodifferentiation. This mechanistic hypothesis has found additional experimental support; the low ee obtained with [BnNMe3]OH (a large cation) as base can be dramatically improved by introducing lithium cations into the system. Also, the complexation of Na+, K+, and Li+ cations by the addition of [15]crown-5 and [18]crown-6 ethers and cryptand 2.1.1 (which selectively bind to these cations and, thus, increase their bulkiness), respectively, to the reaction mixture led to a significant drop in the enantioselectivity of the reaction. The lithium effect has proved useful for enhancing the reduction of different aromatic and heteroaromatic ketones. 相似文献