Tautomeric equilibria for ionized oxamic acid - inhibitor of LDH

Subject Areas : Journal of the Iranian Chemical Research

Ewa D. Raczyńska ^{1 *} , Małgorzata Hallmann ² , Kinga Duczmal ³

1 - Department of Chemistry, Warsaw University of Life Sciences (SGGW), 02-776 Warszawa, Poland
2 - Department of Chemistry, Warsaw University of Life Sciences (SGGW), 02-776 Warszawa, Poland
3 - Department of Chemistry, Warsaw University of Life Sciences (SGGW), 02-776 Warszawa, Poland

Received: 2011-02-26 Accepted : 2011-03-12 Published : 2011-03-31

Keywords: DFT, Oxamic acid, Amide-iminol tautomerism, Ionization, &pi, -electron delocalization,

Abstract :

Amide-iminol tautomerism was studied for ionized oxamic acid (OA+•) in the gas phase using theDFT method with the UB3LYP functional and various basis sets {6-31++G(d,p), 6-311+G(d,p), and augcc-pVDZ}. Among twenty tautomers-rotamers possible for OA+•, eleven isomers were found to bethermodynamically stable. Similarly as for the neutral molecule, ionization (OA → OA+• + e) favors theamidization process (amide ← iminol). Isomerization seems to change solely the conformationalpreferences. π-Electron delocalization in the NCO and OCO moieties is close to that for n-π conjugatedfragments.