DOI: https://doi.org/10.15421/081303
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Tautomerism of 4-hydrazinoquinazolines: vibrational spectra and computational study

Tetiana Yu. Sergeieva, Olexiy Yu. Voskoboynik, Sergiy I. Okovytyy, Sergiy I. Kovalenko, Jerzy Leszczynski

Abstract


The tautomerism of 4-hydrazinoquinazoline and its derivatives was investigated. Geometry and thermodynamic parameters were computed theoretically using Gaussian 03 software. All calculations were performed at the MP2 level of theory using the standard 6-31G(d) basis. Energetics and relative stabilities of tautomers were compared and analyzed in a gas phase. The effect of solvents (1,4-dioxane, acetic acid, ethanol and water) on the tautomeric equlibria was evaluated using PCM. It was determined that solvents induced slight changes in the relative stability. In all cases 4-hydrazinoquinazoline exists predominantly as the amino form. The variation of dipole moments was studied. The anharmonic vibrational wavenumbers for unsubstituted 4-hydrazinoquinazoline were calculated at MP2/6-31G(d) level and compared with experimental data. The modes of IR spectra were assigned. The calculated herein wavenumbers and intensities of amino form are in good agreement with those observed experimentally.      

Keywords


tautomer; 4-hydrazinoquinazolines; ab-initio; IR spectra; vibrational assignment

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