This paper considers the coordination state of boron and aluminum ions in barium aluminoborate glass with a constant ratio of BaO : B 2 O 3 = 0.5 and a variable ratio of Al 2 O 3 : BaO = 0-3. The dependence of the concentrations of boron and aluminum atoms with a variable coordination number on the Al 2 O 3 content was estimated by IR, 11 B and 27 Al NMR spectroscopy. The nonlinear nature of the obtained dependences was attributed to variations in the aluminum oxide properties. At a content of less than 30 mol % Al 2 O 3 serves pri marily as a network former, while an increase in the Al 2 O 3 concentration results in its higher modifying role in the studied glass.

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3,5-Dimethylpyrazole and halogen-containing carboxylic acids in solution give rise to equilibrium between the free molecules and 1 : 1 and 1 : 2 H-complexes. These complexes either have a ion pair-like structure with two equivalent hydrogen bonds O ! ...HN + (1 : 1) or include homoconjugate anion with strong hydrogen bond C3O3H...O3C (1 : 2). At low temperatures, 2 : 1 complexes were detected. The structure and harmonic vibration frequencies of the complexes were calculated in terms of the density functional theory.An important role of strong hydrogen bonds in enzymatic catalysis [133] and molecular self-organization [436] stimulates studies in this line. The problem is complicated by the fact that H-bond systems involved in both cases strongly interact with each other and are dependent on the molecular environment. Pyrazoles are promising model compounds and convenient components for building up supramolecular systems. Due to the presence of an =NN(H) fragment, pyrazole derivatives possess a unique ability to form various self-associates (linear chains, cyclic dimers, trimers, and tetramers, and complexes with proton donor and proton acceptors) in the gaseous phase, in crystal, and in solution [7310]. Structural diversity of such associates and considerable differences in their spectral parameters make it possible to examine the effect of substituents on the geometry and thermodynamic properties of the complexes, interactions between several hydrogen bonds, and specific behavior of IR absorption bands typical of N3H stretching vibrations, chemical shifts and coupling constants in NMR spectra, and H/D-isotope effects.

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