X-ray crystallography and computational studies of the structure of bis-nitrone, 2,5-bis{[methyl(oxido)imino]phenyl}-furan

Bis-nitrone, 2,5-bis{[methyl(oxido)imino]phenyl}-furan prepared by condensation of 2,5-diformylfuran with two equivalents of phenylhydroxylamine can theoretically exist in 10 different structural isomeric forms. The relative energies calculated with AUG-cc-pVDZ and 6-311+G(df, pd) basis sets are used to predict the most stable isomeric form for this molecule. The single crystal X-ray structure analysis confirms this prediction. The bond lengths, angles, and dihedral angles obtained in the crystal structure are in good agreement with the molecular parameters calculated using DFT B3LYP method employing 6-311+G(df, pd) basis set. Population analysis using polar tensors (APT) indicates the traditional N+O− interpretation of the nitrone function whereas Mülliken method fails to show the charge separated structure.