S. F. Bureiko, N. S. Golubev, S. Kucherov
Nov 12, 2007
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Influential Citations
7
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Journal
Journal of Molecular Structure
Abstract
Abstract The results of experimental studies and theoretical calculations of vibrational frequencies and structure of H-bonded associates of N,N- diphenylformamidine and its complexes with carboxylic acids and hydrogen chloride in solution are discussed. The IR and low temperature NMR spectra show the existence of equilibrium between s-trans- monomers and cyclic dimers, such as cyclic H-bonded complexes with carboxylic acids in solution. The complexes with weak acids have molecular structure. The interaction with strong acids and hydrogen chloride results in formation of H-bonded ionic pairs with proton transfer to the N atom of the base. The results of quantum chemical calculations confirm the formation of cyclic molecular complexes with two H-bonds NH…O C and OH…N at the interaction with weak carboxylic acids; the proton transfer along the OH…N bridge was found for the complexes with stronger proton donors. The vibrational frequencies and intensities were obtained also by a version of variational multidimensional anharmonic calculations of vibrational electrooptic parameters in space of normal coordinates. It was shown that this approach is more preferable for calculating the high-frequency XH stretch in systems where the corresponding normal mode is less characteristic and involves motions of many atoms.