IR and PMR Spectrum Analysis of 1-Benzoyl-3-(4 Bromophenyl)-5-Hydroxy-5-Trifluoromethyl-2 Pyrazoline Ligand

Abstract

This study investigates the structural features of 1-benzoyl-3-(4-bromophenyl)-5-hydroxy-5-trifluoromethyl-2-pyrazoline through IR and PMR spectroscopy. While aroyltrifluoroacetylmethanes are known to exist in equilibrium between cis-enol tautomers, the exact behavior and structure of their condensation products with benzoyl hydrazine remain insufficiently explored, particularly under mild, catalyst-free conditions. Addressing this gap, the compound was synthesized via condensation in alcohol solution at room temperature, and its structure analyzed through spectral methods. IR spectroscopy confirmed functional group presence, including hydroxyl (νOH ~3400–3500 cm⁻¹), amide (νC=O ~1660 cm⁻¹), and azomethine (νC=N ~1633 cm⁻¹) functionalities, with additional signals indicative of aromatic and C–F bonds. PMR analysis showed spectral signals corresponding to the 5-oxypyrazoline form with no evidence of tautomeric transitions over time, indicating structural stability in CDCl₃. A quartet signal at δ 93.58 ppm in 13C NMR validated the substitution at position 5 by a trifluoromethyl group, confirming intramolecular cyclization and formation of the 5-oxypyrazoline ring. These results demonstrate that the synthesized ligand adopts a stable cyclic structure both in solid state and solution, with its configuration unambiguously supported by NMR and IR data. The findings contribute to the deeper understanding of structure–property relationships in heterocyclic ligands and offer implications for future coordination chemistry studies involving  transition metals and fluorinated β-diketones.