Investigation of simple and water assisted tautomerism in a derivative of 1,3,4-oxadiazole: A DFT study

نویسنده:
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سال
: 2013
چکیده: Investigation of tautomerism and transition states in a derivative of 1,3,4-oxadiazole (A, B, C and D)

in the gas phase and in solution and in a micro hydrated environment with 1–3 water molecules was

performed by calculations at the DFT-B3LYP/6-311++G(d,p) level of theory. The solvent effect is taken into account via the self-consistent reaction field (SCRF) method. The geometries of four possible tautomers of 5-amino-1,3,4-oxadiazole-2(3H)-one were optimized in the gas phase and solution with polarized continuum model (PCM). It was found that in the gas phase and different solvents, A and C tautomers are the most stable and unstable forms, respectively.

The results show that the tautomeric interconversion C to D has the lowest Gibbs free energy changes

and so the highest equilibrium constant in the gas phase and solution. The equilibrium and rate constants

of intermolecular tautomerism in the absence and presence of 1–3 molecules of water were also calculated. The calculated results show that the presence of water molecules considerably reduces the

barrier energy of the various reactions. Therefore, this water-assisted tautomerism can be performed

fast, especially, with the assistance of two molecules of water.
کلیدواژه(گان): Oxadiazole,Tautomerism,Proton transfer,Solvent effect,DFT calculations,Water assisted
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