Investigação das propriedades de composto de coordenação com ligantes redox ativos tetradentados

Abstract

In the present work, we sought to develop the synthesis of new coordination compounds with cobalt metal and a tetradentate ligand of the active redox type, N, N′-bis (2-hydroxy-3,5-di-tert-butylphenyl) ethylenediamine (H4L). And to complete the coordination sphere, auxiliary nitrogen-type ligands were used using en, py, 2,2'-bpy and phen. The H4L ligand was synthesized following a synthesis already reported in the literature and its characterization was performed with the techniques of IVMIR, 1H NMR, and mass spectroscopy. From this, the ligand was incorporated into coordination compounds and the monocrystalline samples obtained in each synthesis were subjected to X-ray diffraction experiments. Compound I, resulted in two distinct crystalline structures obtained in the same synthesis [Co(H2L)en](H1L) and [Co(H2L)en]HCO3- was, it determined that the active redox ligand when coordinating with the Co presented two structures of SQ-•, with that, the ligand has a -2 charge. What differentiates the structures are the counterion present, in one the ion is bicarbonate in the other and the product of an H4L broken and cyclization named H1L. For compounds II and III respectively [Co3(H3L)2(2,2`-bpy)3Cl2] and [Co(H3L)(H1C)(py)2Cl1], there was the formation of polynuclear compounds, because the ligand suffered oxidation (H3L) thus presenting a favorable site for coordination of a second metal ion. For compound IV, [Co(H2L)phen]Cl, it was not possible to perform XRD experiments, as it did not obtain monocrystalline samples. However, in an attempt to synthesize a precursor compound of cobalt and phen, a crystalline structure has not yet been reported by X-ray diffraction, the di-μ-chloro-bis-[aquachlor(1,10'phenanthroline)cobalt(II)], also, the spectroscopic bands were correlated with their obtained structure.