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Results are presented for a molecular dynamics simulation of melting of the water hexamer from three-dimensional configurations (the book, cage, and prism isomers). The interactions between water molecules are described using two rigid potentials-TIP4P and TIP5P. The isomer geometry is determined using the connectivity matrix of the H-bond network graph. It is found in a numerical experiment that the Lindemann index, which shows the fluctuations in the length of intermolecular bonds, behaves similarly for all the studied initial isomers of the cluster. The melting of the cluster is found to depend on the interaction potential used in the study. For the cluster’s full energy, regions are identified which can be attributed to the premelting phase, which is dominated by the book isomer for TIP4P and ring isomer for TIP5P. The energy region attributed to the quasi-liquid phase of the cluster is shown to be characterized by isomers with ring and linear structures for both of the potentials.

Thermodynamic characteristics are calculated for aqueous alkanolamine solutions that are obtained by substituting alkyl radicals for the protons in the amino group of monoethanolamine and form no hydrogen bond networks. Patterns are found in the variations of the structural properties of the mixtures. A correlation is observed between the entropy and enthalpy characteristics of the water-alkanolamine systems with excess packing coefficients, suggesting that the structural and energy properties of aqueous solutions of these alkanolamines are determined by universal interactions. The concentration curves for the structural and thermodynamic characteristics of the systems are symbatic with the data on water-aprotic amide mixtures. Explanations of this behavior are discussed by comparing the results with the previous data on aprotic amide solutions.

The molecular dynamics simulation of dimers of glycyrrhizic acid (GA) arising from the spontaneous meeting of two GA molecules in water is performed. Shown that the molecules in the dimer are quite close to each other, there is no place between them where another molecule (including water molecule) could fit. The relatively stable structures of dimers are found, which are characterized by the specific values of angles between the terpene skeletons of GA molecules and sugar ends. Due to thermal motion, the spontaneous transitions between these structures occur. The insertion of a molecule of cholesterol in the solution showed that the associates formed from two GA molecules and one cholesterol molecule are, as a rule, one of stable GA dimers with the attached cholesterol molecule.

In the work the structures of fluoride borates demonstrating the substitution with the stoichiometry (BO ₃) ^3- ↔ 3F ^- are analyzed and the specific role of tetrahedral anionic [X ₄] ^4- groups is revealed in this substitution. The possibility of the F-F interaction in [F ₄] ^4- groups uncharacteristic of ionic crystals is confirmed by ab initio quantum chemical simulation of the crystal structure of Ba _{4- x}Sr _{3+ x}(BO ₃) _{4- y}F _{2+3 y}.

In the interaction of basic copper carbonate with optically pure malic acid and 4,4'-bipyridine [Cu ₂( S-mal) ₂(bpy) ₂(H ₂O)]×2.5H ₂O (1) is obtained. The structure of the metal-organic coordination polymer is unique for this class of compounds, which is established by the single crystal X-ray diffraction analysis using synchrotron radiation.

Pyrazolate bridging binuclear copper(II) complex with a heterocyclic azomethyne ligand (a condensation product of 1,3-diaminopropanol-2 with 1-phenyl-3-methyl-4-formyl-5-mercaptopyrazole) is synthesized and structurally characterized. The structure of the complex is compared with the structure of its pyrazolone analogue. It is shown that for the 2 J calculation the use of the previously optimized geometry rather than the geometry from the XRD data results in better agreement with the magnetochemical experiment.

In the reaction of (Et ₄N) ₂[W ₂S ₄Cl ₄] with 1,2-bis(diphenylphosphino)ethane in acetonitrile a new binuclear complex of tungsten(V) [W ₂S ₄Cl ₂(dppe) ₂]×2CH ₃CN is obtained. Its crystal structure is solved in the triclinic space group P-1 with the following unit cell parameters a = 10.1202(16) Å, b = 11.758(2) Å, c = 12.648(2) Å, α = 104.324(5)°, β = 106.469(5)°, γ = 97.587(5)°, V = 1364.9(4) Å ³, Z = 1, with the final refinement parameters R ₁ = 0.0545, wR ₂ = 0.1053. The work describes the synthesis, crystal structure, and Raman spectrum of the [W ₂S ₄Cl ₂(dppe) ₂]×2CH ₃CN complex.

The syntheses, crystal structures and characterization (IR, TGA/DSC) of the isostructural one-dimensional coordination polymers [Ce(C ₇H ₆NO ₂) ₃] _n ( 1) and [Pr(C ₇H ₆NO ₂) ₃] _n ( 2) are described. The metal ions adopt distorted capped square anti-prismatic MO ₉ coordination geometries. The anthranilate ligands bridge the metal ions in bridging-bidentate (O, μ ²-O') mode to generate [010] chains in the crystal and each ligand features an intramolecular N-H⋯O hydrogen bond. It is notable that two very similar, but crystallographically distinct chains appear in the unit cell. Crystal data: 1, C ₂₁H ₁₈CeN ₃O ₆, M _r = 548.51, monoclinic, P2 ₁/ c (No. 14), a = 25.0476(10) Å, b = 7.4924(2) Å, c = 24.6366(7) Å, β = 119.424(1)°, V = 4027.1(2) Å ³, R( F) = 0.037, wR( F ²) = 0.068. 2, C ₂₁H ₁₈N ₃O ₆Pr, M _r = 549.29, monoclinic, P2 ₁/ c (No. 14), a = 25.0077(13) Å, b = 7.4497(3) Å, c = 24.6063(12) Å, β = 119.392(2)°, V = 3994.1(3) Å ³, R( F) = 0.031, wR( F ²) = 0.068.

An analysis is presented for the results obtained in the studies initiated by A. E. Shvelashivili, Corresponding Member, Academy of Sciences of Georgia, and continued by us after he has passed away. The studies are focused on guanidinium and citrate ion containing compounds. It is found that protonation delocalizes the π bond and equalizes the С-N bonds in the guanidine grouping and that the doubly or triply deprotonated citric acid anion in complex compounds acts both as a bi- and tridentate ring-forming ligand.

The X-ray crystallographic analysis of benzoaza-12-crown-4 hydrochloride crystals is performed for the first time: space group Р1, а = 7.7497(4) Å, b = 9.2224(5) Å, c = 10.2395(5) Å, α = 99.3965(10)°, β = 101.8387(11)°, γ = 112.6470(10)°, V = 636,81(6) Å ³, Z = 2, ρ _calc = 1.355 g/cm ³. The conformation of the 12-membered ring of the molecule is determined.