THE STRUCTURE AND CONFORMATIONS OF PIRACETAM (2-OXO-1-PYRROLIDINEACETAMIDE): GAS-PHASE ELECTRON DIFFRACTION AND QUANTUM CHEMICAL CALCULATIONS.
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Quantum chemical calculations.The piracetam molecule is stabilized in the gas phase by an intramolecular hydrogen bond between the N9H2 group and the oxygen O6, bonded to C2. The principal structural parameters (re, Å and \e, degrees; uncertainties are 3rLS values) were found to be: r(C3AC4) = 1.533(1), r(C4AC5) = 1.540(1), r (N1AC5) = 1.456(1), r(C2AC3) = 1.520(1),Abstract
The geometric structure of piracetam was studied by
quantum chemical calculations (DFT and ab initio), gas electron
diffraction (GED), and FTIR spectroscopy. Two stable mirror
symmetric isomers of piracetam were found. The conformation of
pyrrolidine ring is an envelope in which the C4 atom deviates from the
ring plane, the angle between the planes (C3AC4AC5) and
(C2AC3AC5) is 154.1°. The direction of the deviation is the same as
that of the side acetamide group.
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Published
2026-06-28
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