Synthesis, characterization and DFT study of a new family of pyrazole derivatives

Article abstract of DOI:10.1016/j.poly.2014.06.003

This work deals about the synthesis and characterization of compounds containing the pyrazole core belonging to the family of (E)-4-((3,5-dimethyl-1- (4-R-phenyl)-1H-pyrazol-4-yl)diazenyl)benzonitrile, with possible application as ligands in inorganic chemistry. These compounds were obtained by reaction of a substituted arylhydrazine, RC₆H₄NHNH₂, R: 4-OCH₃, 4-CH₃, 4-F, 4-H, 4-Cl, 4-CF₃, 4-CN, 3-Cl, 3-NO₂, 2-Cl and perfluorophenylhydrazine, C₆F ₅-NH₂NH; with a β-diketohydrazone precursor of formula (CH₃CO)₂CNNHC₆H₄4-CN. Analytical techniques (MP and EA) and spectroscopic methods such as UV-Vis, IR, ¹H NMR, ¹³C NMR were employed to characterize the prepared systems. One of the synthesized compounds yielded in ethanol single crystals suitable for X-ray diffraction study. In order to model all the studied compounds and the molecular orbitals involved in the transitions, DFT and TDDFT calculations were performed. The non-variability of the bond distances suggests the robustness of the conjugated structure formed by the RC₆H ₄pyrazoleNNbenzonitrile rings, which is poorly affected by the change of the substituents over the phenyl ring.