Synthesis, structural characterization, and DFT studies of new mixed-ligand iron(III) Schiff-base complexes

Abstract

Cationic iron(III) Schiff-base aquo complex of the type [FeL(H₂O)₂]NO₃ (L = C₁₂H₁₈N₂O₂) was accessed from the interaction of Fe(NO₃)₃ ⋅ 9H₂O with the [N₂O₂] donor Schiff base. Reaction of the aquated complex with bifluoride , thiocyanate (SCN⁻), or azide in 1 : 2 molar ratio in methanolic medium led to the synthesis of anionic mixed-ligand complexes, [FeLX₂] ^{n −} (L = C₁₂H₁₈N₂O₂, X = F, NCS, N₃). The tetradentate Schiff-base ligand was prepared from the condensation of acetylacetone and ethylenediamine following literature method and characterized by spectroscopic and single crystal X-ray diffraction technique. The complexes were characterized using elemental analysis, FT-IR, UV-Vis, mass spectroscopy, and solution electrical conductivity studies. The magnetic susceptibility measurements suggested high-spin Fe(III). The electronic structures of the compounds were analyzed by DFT method using B3LYP/6-31G(d,p) functional and overall, very good agreement between theoretical expectations and experimental data was achieved. The electrochemical behavior of the complexes was examined by cyclic voltammetric method.

Keywords:

• Schiff base
• Mixed-ligand iron(III) complex
• DFT
• Acetylacetone
• Ethylenediamine

Acknowledgments

The authors express sincere thanks to SAIF, NEHU, Shillong and SAIF, CDRI, Lucknow, India for providing analytical and spectral results.