Synthesis, structural and vibrational properties of 1-(4-Fluorobenzoyl)-3-(isomeric fluorophenyl)thioureas

The 1-(4-Fluorobenzoyl)-3-(isomeric fluorophenyl)thioureas (1–3) were prepared by the reaction of 4-fluorobenzoyl isothiocyanate produced in situ with isomeric fluoroanilines in dry acetonitrile in good yields. The novel compounds were characterized by multinuclear (1H and 13C) NMR, elemental analyses and FTIR spectroscopy techniques. Structural and conformational properties of compounds 1–3 have been analyzed using a combined approach including X-ray diffraction, vibrational spectra and theoretical calculation methods. The carbonyl and thiourea groups are almost planar and the conformation adopted by the CS and the CO double bonds is antiperiplanar, in a conformation which is stabilized by intramolecular NH⋯O hydrogen bond. Crystal packing shows molecules connected by intermolecular NH⋯SC hydrogen bonds to form centrosymmetric dimers.