Síntese e caracterização de polímeros de coordenação envolvendo o ácido 1,2,4,5-benzenotetracarboxílico, ligantes nitrogenados e metais de transição

Abstract

This work describes the synthesis and characterization of coordination polymers with Mn2+, Co2 +, Cu2 + and Zn2 + from the first row transition using 1,2,4,5-benzenetracarboxylic acid (H4BT) and 1,3-diamino propane (PA), 1,4-diamino butane (BA), 4- aminbenzoic acid (Hpaba) and pyrazine (PZ) Amines. Three previously unpublished products have been characterized by analytical and spectroscopic techniques such as elemental analysis (CHN), thermogravimetric analysis (TG) and infrared (IV) and Raman vibrational spectroscopies. These compounds were obtained as single crystals and had their structures determined by single crystal X-ray diffraction (MXRD) which also allowed comparison with the diffractograms obtained by powder X-ray diffraction (PXRD). The thermogravimetric analysis showed that these compounds are hydrated with coordination water molecules and/or stabilizing the crystalline lattice. The coordination modes of the carboxylate groups could be inferred by calculating Δν (νassim COO- - νsim COO-). In these compounds the great versatility of the BT4- ligand and various coordination modes (monodentate, bridged bidentate and chelate bidentate) of its carboxylate groups were observed in the formation of coordination polymers. The single crystal X-ray diffraction technique revealed that two compounds are anionic and isostructural three-dimensional coordination polymers while the third compound is anionic and two-dimensional coordination polymer. The amines used in the syntheses, although not coordinated to the metallic centers, stabilize the charges of their networks and form supramolecular arrangements by hydrogen bonds with atoms of molecules coordinated to the metallic centers. The multidimensional polymers obtained had their structures simplified and topologically classified.