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The essence of the electron-proton effect is clarified by the example of donor-acceptor complexes. It is shown that this effect plays a universal role in accelerating dark and photochemical processes due to interaction between electron and proton excitations.

The behavior of structures of H₂O crystalline ices Ih, Ic, XI, VII, VIII, VI is studied in molecular dynamics experiment using the potential offered by Poltev and Malenkov. The behavior of the system consisting of one of the two identical interpenetrating, but without any common hydrogen bonds, water frameworks comprising the ice VI structure is also simulated. As a result of simulations, the ice VII structure has collapsed, whereas other systems proved to be stable. The reasons of instability of the ice VII and previously studied ice IV structures in molecular dynamics experiments are discussed. Based on the simulation results of the above-mentioned ices and previous simulation of ices II, III, IX, IV, and XII, the general regularities of dynamic properties of water molecules in crystalline water ices are formulated. Unreliability of results obtained by molecular dynamics in the investigation of self-organizing processes in aqueous systems is shown.

A significant increase in the stretching band intensity of trichloromethane in IR spectra of its solutions in acetone with increasing acetone mole fraction indicates the formation of hydrogen bonds between their molecules. The integral absorption coefficient (α) of this vibration is calculated. Experimental values of α are approximated by a theoretical dependence using the nonlinear least-squares method; association parameters are obtained. The relative volume fractions of H-bonded and free trichloromethane molecules are calculated depending on the total trichloromethane volume fraction in solution. The structure of the H-bonded associate is determined by quantum chemical calculations.

Quantitative X-ray diffraction analysis of different parts of the coating on titanium obtained by cumulative explosion is performed. The examination of microregions of the coating sized from 1 mm to 0.1 mm reveals that the phase based on the cubic cell of titanium nitride dominates in the upper layers. The predominance of this phase in some regions of the coating provides their increased microhardness. Crystal chemical and EDX analyses indicate the development of non-stoichiometric phases of complex composition. The problem of site occupation factors of light atoms arising in the full-profile refinement of powder X-ray patterns is discussed.

Crystal structures of (NH₄)₃ZrF₇ (I) and (NH₄)₃NbOF₆ (II) are refined by X-ray diffraction at room temperature. The compounds are isostructural and belong to the structural type of elpasolite: space group F23; a(I) = 9.4185(3) Å, а(II) = 9.3371(5) Å; V(I) = 835.50(5) ų, V(II) = 814.02(8) ų; Z = 4; R(I) = 0.0145, and R(II) = 0.0138. The refinement of the structures in the space group Fm3m yields abnormally short X-X distances in the pentagonal bipyramid MX₇ (X = F, O). The oxygen atom in II is identified by nb-X distances and occupies one of the axial vertices of the bipyramid. The Nb atom in II is statistically distributed over the position 24f, while Zr in I resides in the symmetry center. The pentagonal bipyramid MX₇ has six independent orientations in I and twelve in II. One of three crystallographically independent ammonium groups of the structures is disordered over six or twelve equivalent orientations.

X-ray diffraction structural study is carried out for crystals of a heterobimetallic complex derived from lead(II) hexafluoroacetylacetonate and copper(II) 2-methoxy-2,6,6-trimethylheptan-3,5-dionate prepared by co-crystallization of Pb(hfa)₂ and trans-Cu(zis)₂. In the novel compound Cu(zis)₂⋅Pb(hfa)₂ the copper complex is found to have cis-configuration. It is demonstrated that the main structural motif of this complex is coordination dimers Cu(zis)₂⋅Pb(hfa)₂ joint in polymeric chains of alternating molecules of the complexes. Crystal data for Cu(zis)₂⋅Pb(hfa)₂: a = 9.848(2) Å, b = 23.871(5) Å, c = 18.289(4) Å, β = 100.23(3)°, space group P2₁/n, Z = 4, d_x = 1.701 g/cm³. The distance Pb-Cu in the dimer is 3.68 Å.

A novel compound of {[(C₆H₅)NH]₂C=NH(C₆H₅)}[B(C₆H₅)₄]⋅C₂H₅OH is prepared and examined by single crystal X-ray diffraction. Crystal data: C₄₅H₄₄BN₃O, M = 653.64, monoclinic, space group P2₁/с, unit cell parameters: a = 24.375(2) Å, b = 17.5829(15) Å, c = 18.090(1) Å, β = 105.277(2)°, V = 7479.0(11) ų, Z = 8, d_calc = 1.161 g/cm³, T = 293 K, R₁ = 0.064. The structure contains two crystallographically independent cations, two anions, and two solvate ethanol molecules. Three types of interactions occur between them: interionic N-H(N)^…π and N(H)^…π^…H(C), π-delocalized system of Ph rings of the anions, and interaction of ions with ethanol molecules N-H^…O-H(O)^…π. The compound is characterized by IR and luminescence spectra. At room temperature, the emission intensity grows with time of exposure to UV irradiation.

3-(1-Amino-2,2,2-trifluoroethylidene)-1,1,4,5,6,7-hexafluoroindan-2-one (2) is synthesized by the interaction between 3-(1-amino-2,2,2-trifluoroethylidene)-2-imino-1,1,4,5,6,7-hexafluoroindan (1) and isopropylnitrite, and 2-amino-1,1,4,5,6,7-hexafluoro-3-trifluoroacetylindene (3) is prepared by hydrolysis. Single crystals are grown, and the molecular and crystal structure of enaminoketones obtained, the complex of compound 2 with 1,4-dioxane, and the complex of compound 3 with pyridine is studied. DFT calculations have been performed to find the complex formation energies of compounds 2 and 3 with dioxane and pyridine in the gas phase.

X-ray diffraction is applied to investigate metallic cobalt obtained by the reduction of nanocrystalline particles of Co₃O₄. The particles of metallic cobalt have a high concentration of stacking faults, i.e., violations of the layer packing sequence ABABAB…, which is seen in X-ray diffraction patterns as anisotropic broadening of diffraction peaks. Simulation of the diffraction patterns of α-Co with a different concentration of stacking faults is carried out.

This contribution provides the theoretical background for the structure-determining role of hydrogen bonding in the formation of a near-surface layer of titania nanocrystallites, previously revealed by the authors in the investigation of IR experimental spectra of two-component solid mixtures of nanocrystalline titanium dioxide with benzophenone or 4-pentyl-4′-cyanobiphenyl. DFT calculations (B3LYP) in 6-31+G(d) basis set is used to simulate the structure and IR spectra of free molecules of water, 4-pentyl-4′-cyanobiphenyl, benzophenone and their Н-complexes formed in the near-surface layers of titania nanocrystallites due to presence of water adsorbed on their surfaces. Using the results of simulation and analysis of IR spectrum bands corresponding to stretching vibrations of polar bonds О-H, С=О, С≡N, the formation mechanism of near-surface layers of titania nanocrystallites in the considered heterogeneous two-component systems is theoretically substantiated: they are formed by hydrogen-bonded complexes involving components of the mixture and water.