Tautomerism and Spectral Properties of 2‐Anilinomethylenecyclopentane‐1,3‐Dione According to the Data of Quantum‐Mechanical Calculations, IR Spectroscopy, and Secondary Isotopic Effects in the 13C NMR Spectra

Abstract

Using the methods of IR spectroscopy, 13C NMR spectroscopy, and quantum‐mechanical methods (semiempirical AM1 and PM3 methods and the method of the density functional theory), we have investigated the tautomerism and spectral properties of 2‐anilinomethylenecyclopentane‐1,3‐dione. It is shown that this compound in crystals and solutions in CCl4 and CHCl3 exists in the form of a tautomer with an exocyclic arrangement of the C=C bond and a NH group participating in the formation of an intramolecular hydrogen bond with a carbonyl group of the carbocycle.