Synthesis and Characterization of Zn(II) Complexes of 2-(7-Bromo-2-oxo-5-phenyl-2,3-dihydro-1<Emphasis Type="Italic">H</Emphasis>-1,4-benzodiazepin-1-yl)acetohydrazide and Its Condensation Products with Pyruvic Acid and Isatin

The systems ZnCl₂–2-(7-bromo-2-oxo-5-phenyl-2,3-dihydro-1H-1,4-benzodiazepin-1-yl)acetohydrazide (Hydr)–propan-2-ol, ZnCl₂–Hydr–pyruvic acid (HPv), and Zn(CH₃COO)₂–Hydr–isatin(HIz)–propan-2-ol were studied. Optimal synthesis conditions were determined, and the complexes [Zn(Hydr)₂Cl₂], [Zn(HydrHPv)₂Cl₂], and [Zn(HydrIz)₂] were isolated. The complexes were characterized by elemental analysis, thermogravimetry, IR spectroscopy, and mass spectrometry. The electrical conductivities of the complexes were measured. The local environment of the central atom in the coordination entity was determined by X-ray absorption spectroscopy.     

Synthesis and structure of new Am ? 1Bi2BmO3m + 3 (m = 3) phases

Six new polycrystalline bismuth-containing layered perovskite-like oxides described by the general formula A _m − 1Bi₂B _m O_{3m + 3} (m = 3) were synthesized by high-temperature solid-state reactions. The unit-cell parameters of these compounds were determined as a = 5.438(9) Å, b = 5.462(7) Å, and c = 33.08(6) Å for Bi₄Ti₂Nb_0.5Fe_0.5O₁₂; a = 5.408(6) Å, b = 5.425(9) Å, and c = 32.85(6) Å for Ca_0.5Bi_3.5Ti_2.75W_0.25O₁₂; a = 5.457(0) Å, b = 5.482(2) Å, and c = 32.75(2) Å for NaCaBi₂Nb₃O₁₂; a = b = 3.826(2) Å and c = 32.82(6) Å for Ca_0.25Th_0.25Bi_3.5Ti₃O₁₂; a = b = 3.816(2) Å and c = 32.81(5) Å for Nd_0.5Gd_0.5Bi₃Ti₃O₁₂; and a = b = 3.826(4) Å and c = 32.95(8) Å for Th_0.5Bi_3.5Ti_2.5Ga_0.5O₁₂. The compositions of these compounds are based on the composition of the basic Bi-containing layered perovskite-like Bi₄Ti₃O₁₂ oxide in which Bi^III and Ti^IV atoms are partially or completely replaced with other atoms. The experimental and calculated interplanar spacings determined from X-ray diffraction patterns and the reliability factors of their indexing are reported. __________ Translated from Kristallografiya, Vol. 48, No. 3, 2003, pp. 450–457. Original Russian Text Copyright ? 2003 by Geguzina, Shuvayev, Vlasenko, Shuvayeva, Shilkina. This study was presented at the symposium “Order, Disorder, and Properties of Oxides” (ODPO), Sochi, Russia, 2002.     

New ferro-and antiferromagnetic complexes of tridentate azomethines with copper

Tridentate azomethine ligands with N₂O₄ and N₃donor atoms and their copper complexes were synthesized and characterized. The dimeric structure of copper(II) chelates was confirmed by EXAFS studies. Complexes based on 2-tosylaminobenzaldehyde azomethines tend to undergo ferromagnetic exchange, whereas similar salicylaldehyde derivatives have antiferromagnetic exchange.     

1,3,2‐(2H)‐dioxaborine polymethine dyes on the base of dehydroacetic acid — effective fluorescent amine probes

A number of new polymethine dyes based on the boron difluoride complexes of dehydroacetic acid and 3‐acetyl‐4‐hydroxypyridone has been synthesized. Their spectral‐luminescent properties have been investigated. The reaction of obtained merocyanines with primary and secondary amines has been studied. These low fluorescent dyes gave highly fluorescent open chain products, which on further heating cyclized to weakly fluorescent pyridone dyes.     

Molecular design of new magnetically active copper complexes with heteroaromatic schiff bases and azo compounds

Copper chelates with tridentate ligands containing pyridine or pyrazole ring at the azomethine or azo fragment were synthesized by chemical electrochemical methods, and their structure was characterized by the EXAFS spectra. Thermal magnetochemical analysis of the complexes revealed antiferromagnetic exchange interaction in all complexes. The exchange interaction parameter of the complex containing an N-tosylamino group in the ortho position with respect to the azomethine group is much lesser than that of the corresponding complex having an oxygen atom in the same position. The copper chelate derived from azopyrazole ligand shows low-temperature ferromagnetic phase transition.     

An X-ray spectral and theoretical study of the electronic structure and features of interatomic interactions in phenoxysilanes

The electronic structure and features of interatomic interactions providing the Si–O–C₆H₅ bonds in H_4-nSi(OC₆H₅)_n (n = 1–4) were studied by a combined analysis of the X-ray emission and photoelectron spectroscopic data and the results of quantum-chemical calculations. Theoretical calculations were carried out using the density functional theory. The distributions of the density of states were constructed, the correlation energy diagrams were presented, and the main types of interatomic interactions in phenoxysilanes were revealed.     

Synthesis,structure, and photoluminescence properties of molecular complexes of bis(4-formyl-3-methyl-1-phenyl-1<Emphasis Type="Italic">H</Emphasis>-pyrazol-5-olato)cadmium(II) with aminoquinolines and 1-aminoisoquinoline

Molecular complexes of bis(4-formyl-3-methyl-1-phenyl-1H-pyrazol-5-olato)cadmium(II) with isoquinolin-1-amine, quinolin-3-amine, 4,6-dimethylquinolin-5-amine, and quinolin-6-amine have been synthesized, and their structure was studied by IR, UV, ¹H NMR, and X-ray absorption spectroscopy. Photoluminescence properties of the complexes have also been examined.     

Implicit operator differential equations and applications to electrodynamics

A cylindrical waveguide with layered dispersive medium is considered. An implicit operator differential equation of second order is obtained by separating variables in the corresponding boundary‐value problem for Maxwell's equations. Existence and uniqueness theorems are proved and explicit formulae for solutions are given. The spectral theory of operators and operator sheaves are used. Copyright © 2000 John Wiley & Sons, Ltd.     

Dielectric relaxation in layered oxides of the Aurivillius phase family

Two new polycrystalline layered oxides Bi_2.33Ca_0.17Nb_1.33W_0.17O_7.5 and Bi_2.25Ca_0.25Nb_1.25W_0.25O_7.5, in which the number of perovskite layers is equal to 1.5, have been synthesized. It has been revealed using X-ray powder diffraction analysis that both compounds have a single-phase composition and exhibit a structure of Aurivillius phases with orthorhombic unit cells corresponding to space group Cmm2. The analysis of the temperature dependences of the permittivity in the frequency range from 1 kHz to 1 MHz has demonstrated that these compounds are characterized by relaxor properties. This manifests itself in the frequency dispersion of the ferroelectric-paraelectric transition temperature and high values of the diffusivity parameter: γ = 1.75 and 1.82.     

The electronic structure of iron carbonyl complexes as probed by X-ray emission spectroscopy and quantum-chemical calculations

The electronic structure of the polynuclear iron carbonyl complexes [Et₂N][Fe₄N(CO)₁₂], [Et₄N]₂[Fe₅C(CO)₁₄], and [Et₄N]₂[Fe₆C(CO)₁₆] has been studied by X-ray emission spectroscopy and quantum-chemical calculations. The fine structure of the FeKβ₅ X-ray emission spectra characterizes the distribution of iron valence p electrons over the molecular orbitals of the compounds. Comparison of the fine structure of the FeKβ₅ X-ray emission spectra with the densities of states of all atoms in the molecules has made it possible to determine in detail the character and specific features of chemical bonding in the complexes.