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Objectives. The paper is devoted to the crystal structure characterization of 5-methyl-2-phenyl4H-pyrazol-3-one (compound I) and 2-(4-chlorophenyl)-5-methyl-4H-pyrazol-3-one (compound II).Methods. Single-crystal X-ray diffraction studies and theoretical calculations: Density functional theory and quantum theory of atoms in molecules.Results. In the solid state, the crystal structure of compound I is characterized by the alternation of OH and NH tautomers connected via O–H---O and N–H---N hydrogen bonds. For compound II, the existence of chains built from the NH monomers via hydrogen bonding can be explained by the peculiarities of cooperative effects. In the framework of quantum theory of atoms in molecules, the following topological characteristics are calculated for all dimers: electron density, Laplacian of electron density, density of kinetic, potential, and total energy in the critical point of the intermolecular hydrogen bond. It is concluded that the hydrogen bond in dimers 1–4, 7 (compound I), and 8–11 (compound II) can be assigned to the intermediate (between covalent and dispersion types) interaction owing to hydrogen bond formation with the participation of electronegative oxygen- (and/or nitrogen-) atoms, whereas H-bond in dimers 5 and 6 (compound I) can be attributed to the dispersion one (no hydrogen bond formation or weak H-bond formation), and it represents the weak interaction, being in agreement with length for intermolecular hydrogen bond in dimers. The electron density and total energy density values demonstrate that the strongest intermolecular H-bonds take place in dimers 1 (OH---O), 4 (OH---O), 7 (OH---N), 8 (OH---O), 9 (NH---N), and 11 (OH---N). The results obtained for compounds I and II are compared with data for antipyrine (1,2-dihydro-1,5-dimethyl-2-phenyl-3H-pyrazol-3-one; compound III)Conclusions. An important role of intermolecular hydrogen bonding in the crystal packing, molecule association and self-organization via dimer- or more extended species formation has been demonstrated.

The present review is devoted to consideration and generalization of a number of synthetic methods for lanthanide oxoiodides preparation as well as to consideration of their structural particularities and thermal stability. Phase diagrams with the participation of REE oxoiodides, alkaline metal iodides or silver iodide are given and discussed. All the systems are characterized by the solid solution formation on the basis of the pure compounds, while the systems with the participation of alkaline metal iodides are characterized by the formation of incongruent melting compounds. Structural data concerning oxoiodides of lanthanides with different oxidation states and with the participation of some other elements (carbon, nitrogen, barium, osmium, etc) are present and overviewed. Possible areas of application (catalysis, X-ray detectors, medical diagnostics) including distinct luminescent properties of Ce-, Pr-, Nd-, Sm-doped REE oxoiodides are underlined.

Searching the quantitative structure–property relationships (QSPR) is one of the most important tasks of the contemporary theoretical chemistry. The models obtained may be used for prognosis of the chemical substances properties on the basis of their structure and for searching compounds with predetermined properties. About 980,000 structure–property linear models have been constructed for parameter lgKa (Ka – acidity constant) of a number of organic compounds. Different training and test sets obtained by means of multiple random halving the initial set of compounds have been used to desigh these models. Molecular descriptors have been selected from some set of topological molecular parameters reflecting different particularities of molecular structures. The Wiener index, the generalized weighted connectivity index, the number of hydrogen atoms, some spectral characteristics of graph, representing molecule, etc. are among these parameters. About 90 the best models have been selected on the basis of some quantitative criterium, characterizing the model precision both on training and test sets. These models have been used for evaluation of lgKa for other compounds not included into the initial set of compounds, by calculation of lgKa for every model and averaging the results obtained. Besides, the structural particularities possessing the most significant influence on the given property have been derived on the basis of analysis of these models. The computer program Wolfram Mathematica 8 has been used in this work.

Data on the synthesis, IR-spectra, powder XRD studies as well as the results of quantum-chemical calculations for [Ln(AP)6]I3, [Ln(AP)6](ClO4)3 (Ln = Sc, Y, La–Nd, Sm–Lu; AP – antipyrine, C11H12N2O) are presented. It was demonstrated that coordination of the ligand takes place through an oxygen atom of the antipyrine carbonyl group. The calculated results (DFT/PBE/L11) are in good agreement with the experimental ones.

The synthesis and data of the study of new complexes of samarium bromides with carbamide, [Ho(Ur)4(H2O)4]Br3 (I), [Ho(Ur)6(H2O)2]Br3 (II) and [Ho(Ur)4Cl3] (III), by IR spectroscopy and X-ray diffraction analysis are presented. For these compounds, coordination with metal occurs through the oxygen atoms of the water and carbamide molecules. The coordination polyhedra for I and II are distorted tetragonal antiprisms. In III, we have found inner-sphere coordination of four carbamide molecules and three chloride ions (the coordination polyhedron is a pentagonal bipyramid). The coordination of four carbamide molecules in I-III does not change their planar structures, but in II two carbamide ligands are distorted. Many hydrogen bonds are observed in the structures of complexes I-III.

Data concerning the synthesis, IR-spectra, and single crystal X-ray studies for neodymium iodide and gadolinium iodide - thiourea complexes of the general composition [Ln(H2O)9]I3 · 2CS(NH2)2 (Ln = Nd, Gd) are presented. It has been demonstrated that in the solid state the title compounds are composed from [Ln(H2O)9]3+cations (polyhedron: monocapped tetragonal antiprism) as well as from non-coordinated thiourea molecules and iodide ions. Due to hydrogen bond formation mutually perpendicular flat molecules of thiourea are combined into goffered layers, nonaaquacations of lanthanides and iodide-ions being located in the cavities between these layers. The existence of hydrogen bonding between the mentioned species has been underlined.

In the framework of the statistical approach the non-linear «structure - melting point» model for pyrazolone derivatives is constructed. Number of topological parameters calculated from the structural formula was used for the quantitative description of the molecular structure. The results of calculation of the melting points for a series of compounds of considered class are reported.

The program СОРЕ was developed on the basis of VBA Excel language for carrying out the statistical processing of outcomes of experiments. The program significantly simplifies and accelerates routine processing of experimental data

Complexes of lanthanum, cerium, neodymium, samarium, europium, terbium, erbium, thulium, ytterbium, lutetium iodides with carbamide and iodine were synthesized and characterized by chemical analyses, IR and Raman spectroscopy, electric conductivity (from –195.,8 to 20°С). These compounds are found to include complex cations and polyiodide anions.

An alternative approach for description of phase equilibria in quaternary systems MI2 – Ur – I2 – H2O at 00 С as compared with the published one («Vestnik MITHT», 2006, №1, pp.66-70) is given