H/F replacement in secondary alcohols of sydnones as examples of isostructural OH⋯OC hydrogen bonded dimer structures†

Two new crystal structures of 4-acetyl-3-aryl-sydnones and their corresponding secondary alcohols obtained by hydrogenation of the acetyl ketone group were obtained and investigated by single-crystal X-ray diffraction, Hirshfeld analysis and DFT. Rather scarce in the CCDC database, 4-acetyl-3-aryl-sydnones presented interesting crystal features and by replacing the CO group with a secondary O–H group, two new isostructural compounds were obtained revealing H/F isosteric replacement and strong O–H⋯OC (sydnone) dimers, as well as attractive anti-parallel sydnone⋯sydnone electrostatic interactions directing the molecular packing. The OH⋯OC hydrogen bonds detected previously by IR spectroscopy were confirmed by X-ray diffraction analysis. By changing the position of the secondary alcohol, from the sydnone ring to the para position of the phenyl ring, infinite OH⋯OC driven arrays are obtained instead of dimers. DFT calculations were employed to investigate the H-bonded dimers and find reliable evidence of isostructurality by H/F replacement.