Tautomeric, spectroscopic, DFT calculations and X-ray studies on O2N-4-C6H4–NHNC(COCH3)2

This paper deals with the structural and tautomeric studies on O2N-4-phenyl hydrazone derivative of acetylacetone, of formula O2N-4-C6H4NHNC(COCH3)2, I, using IR, 1H NMR and 13C NMR spectroscopies, X-ray diffraction analysis and quantum mechanical calculations. The crystallographic data show that this compound has a β-diketohydrazone structure, containing an intramolecular H-bond assisted by resonance (RAHB), with N⋯O distance of 2.6025(16) Å. These results are in agreement with the spectroscopic studies and with theoretical calculations. The collected information confirms that I shows the same structure in CDCl3 solution, solid state and gaseous phase.