Structural characterization of a new dioxamic acid derivative by experimental (FT-IR, NMR, and X-ray) analyses and theoretical (HF and DFT) investigations.

• Autor(a) principal: Souza, Gilmar Pereira de
• Data de Publicação: 2012
• Outros Autores: Konzen, Cibele, Simões, Tatiana Renata Gomes, Rodrigues, Bernardo Lages, Alcântara, Antônio Flávio de Carvalho, Stumpf, Humberto Osório
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFOP
• Texto Completo: http://www.repositorio.ufop.br/handle/123456789/2031
• topic: Molecule-based magnet; Dioxamic acids; Supramolecular chemistry; X-ray crystal structure

Very few investigations concerning the crystal structure and chemical properties of dioxamic acids have been related in the literature. This work describes the chemical properties of ortho-phenylenebis(oxamic acid) (2) and its new derivative, hydrogeno ortho-phenylenebis(oxamato) benzimidazolium (3) using experimental (FT-IR, NMR, and X-ray single crystal diffraction) and theoretical (HF/3-21G_ and B3LYP/ 6-31G_ calculations) methodologies. Compound 2 displays intramolecular hydrogen bonding between the hydrogen of an amide group and the oxygen atom of another amide group present in the structure. Compound 3 was prepared by a newly developed synthetic route involving decomposition of the dioxamic acid in solution without the presence of metallic ions. Thermodynamic calculations indicate a process via two successive hydrolyzes of the amide groups of 2, followed by condensation with formic acid and finally dehydration. The structure of 3 was solved by X-ray single-crystal diffraction and it consists of meso-helical chains stabilized by intra and intermolecular hydrogen bonds and p–p stacking interactions.