Diverse coordination of aroylhydrazones toward iron(III) in solid state and in solution: spectrometric, spectroscopic and computational study.

The coordination properties of N'-(2-hydroxy-3-methoxyphenylmethylidene)-3-pyridinecarbohydrazide (HL1), N'-(2-hydroxy-4-methoxyphenylmethylidene)-3-pyridinecarbohydrazide (HL2) and N'-(2-hydroxy-5-methoxyphenylmethylidene)-3-pyridinecarbohydrazide (HL3) toward Fe(III) ions were studied by computational, spectrometric (MS) and spectroscopic methods (UV-Vis, IR and Raman spectroscopy) in solid state and in solution. Free ligands were present in keto-amine form with intramolecular H-bond. In MeOH:HO 1:1 system, the 1:1 complexes with Fe(III) were formed, characterized by lgK ≥ 6.