Síntese e caracterização do complexo de ferro II contendo ligantes heterocíclicos nitrogenados

Abstract

This work aimed to synthesize and characterize an iron (II) complex with nitrogenous heterocyclic ligands. The complex was characterized by spectroscopy in the visible ultraviolet and medium infrared regions. Qualitative tests using silver nitrate and solubility were performed to aid in the determination of the structural composition of the complex. Computational studies were performed to determine the energy of the isomers and thus determine the probable structure of the complex. Analysis with silver nitrate indicated that the chlorides are coordinated to the metal indicating the formation of a neutral complex. The solubility test indicated that the complex has low solubility in the solvents tested which is characteristic of neutral coordination compounds. The visible ultraviolet absorption spectrum allowed to verify a band profile at 497 nm attributed to the MLCT type. The spectroscopy in the middle infrared region showed bands characteristic of the bipyridine and isonicotinamide ligands and showed that the coordination of the ligands to the metallic center occurred through the nitrogen atom of the pyridine rings. The theoretical study of the isomers was carried out using the computational calculation to optimize the structures of the isomers and simulation of spectroscopic techniques. These studies provided important parameters that helped to distinguish a possible geometric structure (cis or trans). The thermal analysis study TG-DTA was used in order to verify the oxidation state of the metal.