Original scientific paper

A Theoretical and Experimental Study of Dipole Moments of 3-Aminofurazans

Rostislav E. Trifonov ; St. Petersburg State Institute of Technology, Moskovskii av. 26, 198013, St. Petersburg, Russia
Aleksandr V. Gaenko ; St. Petersburg State Institute of Technology, Moskovskii av. 26, 198013, St. Petersburg, Russia
Sergei N. Vergizov ; St. Petersburg State Institute of Technology, Moskovskii av. 26, 198013, St. Petersburg, Russia
Michail B. Shcherbinin ; St. Petersburg State Institute of Technology, Moskovskii av. 26, 198013, St. Petersburg, Russia
Vladimir A. Ostrovskii ; St. Petersburg State Institute of Technology, Moskovskii av. 26, 198013, St. Petersburg, Russia

Abstract

Dipole moments of a series of 3-amino-5-R-furazans (R = H, NH₂, OCH₃, CH₃, N₃, COOH, COOCH₃, NO₂) have been determined experimentally and also calculated by means of HF ab initio (STO-3G, 3-21G, 4-31G, 6-31G, 6-31G**/4-31G, 6-31G** levels) and semiempirical (MNDO, AM1, PM3) quantum chemical methods. It was shown that semiempirical AM1 and PM3 methods provide generally good agreement with the experimental values of dipole moments. On the other hand, a satisfactory description of this aminofurazan property by ab initio method is observed only in the case of calculation levels with the electron correlation and the polarization function included. For these compounds amino-imino tautomeric equilibrium is strongly shifted towards the amino-form. 3-Aminofurazan-4-carboxylic acid and its methyl ester exist in dioxane or benzene solutions at least as a mixture of two different s-cis- and s-trans-conformers stabilized by conjugation and hydrogen bonding.

Keywords

aminofurazans; dipole moment; tautomerism; conformation

Hrčak ID:

103094

URI

https://hrcak.srce.hr/103094

Publication date:

30.6.2003.

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