Structure and photochemistry of a novel tetrazole-saccharyl conjugate isolated in solid argon

• Autores: Ismael, Amin; Borba, Ana; Duarte, Luís Vítor; Giuliano, Barbara Michela; Gomez Zavaglia, Andrea; Cristiano, María Lurdes Cristina
• Año de publicación: 2012
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Matrix Isolation; Molecular Structure; Photochemistry; Saccharin; Tetrazole
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

A combined matrix isolation FTIR and theoretical DFT/B3LYP/6-311++G(3df, 3pd) study of the novel synthesised tetrazole-saccharyl conjugate 2-[1-(1H-tetrazol-5-yl)ethyl]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide [1-TE-BZT] was performed. In the gas phase, at room temperature, the compound exists as a mixture of six isomeric forms (four conformers of 1H tautomer and two conformers of 2H tautomer). According to theoretical calculations, conformers 1H were the most stable and the relative energies among the three most stable forms are lower than 4 kJ mol -1. These conformers benefit from stabilising intramolecular hydrogen bonds-like interactions involving the 1H of the tetrazole ring and the carbonyl oxygen of the saccharyl moiety. The photochemistry of 1-TE-BZT in solid argon was investigated and theoretical DFT/B3LYP/6-311++G(3df,3pd) calculations also helped in assignment of the experimental bands. A quick consumption of the compound occurred after irradiation of the matrix with UV laser light at λ = 275 nm. Three photofragmentation pathways were proposed, one leading to 2-[1-(1H-diaziren-3- yl)ethyl]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide and molecular nitrogen, a second one giving 2-(1,1-dioxide-3-oxo-1,2-benzisothiazol-2(3H)-yl) propanenitrile and azide, and a third one involving loss of azide from the tetrazole ring and decarbonylation of the saccharyl ring of 1-TE-BZT to give acrylonitrile and 7-thia-8-azabicyclo[4.2.0] octa-1,3,5-triene 7,7 dioxide. The comparison of the relative intensities of the bands of the photoproducts obtained from the three channels allowed us to consider the latter pathway, involving an unprecedented photocleavage of the benzisothiazole (saccharyl) ring, as the preferred photodegradation channel of 1-TE-BZT.
Fil: Ismael, Amin. University of Algarve. Department of Chemistry and Pharmacy; Portugal
Fil: Borba, Ana. University of Coimbra. Department of Chemistry; Portugal
Fil: Duarte, Luís Vítor. University of Coimbra. Department of Chemistry; Portugal
Fil: Giuliano, Barbara Michela. University of Coimbra. Department of Chemistry; Portugal
Fil: Gomez Zavaglia, Andrea. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. University of Coimbra. Department of Chemistry; Portugal
Fil: Cristiano, María Lurdes Cristina. University of Algarve. Department of Chemistry and Pharmacy; Portugal