Infrared spectrum and UV-induced photochemistry of matrix-isolated 5-methoxy-1-phenyl-1H-tetrazole

• Autor(a) principal: Gómez-Zavaglia, Andrea
• Data de Publicação: 2006
• Outros Autores: Reva, I. D., Frija, L., Cristiano, M. L. S., Fausto, R.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Texto Completo: https://hdl.handle.net/10316/5085; https://doi.org/10.1016/j.jphotochem.2005.10.012
• topic: 5-Methoxy-1-phenyl-1H-tetrazole; 3-Methoxy-1-phenyl-1H-diazirene; Phenylazide; 1-Aza-1,2,4,6-cycloheptatetraene; Methylcyanate; Tetrazole ring cleavage; Matrix isolation IR spectroscopy; DFT(B3LYP)/6-311++G(d,p) calculations

The molecular structure, vibrational spectra and photochemistry of 5-methoxy-1-phenyl-1H-tetrazole (5MPT) were studied by matrix isolation infrared spectroscopy and DFT(B3LYP)/6-311++G(d,p) calculations. According to the calculations, only one double degenerated-by-symmetry minimum exists in the ground state PES of the compound. In this structure, the dihedral angle between the two rings (phenyl and tetrazole) is ca. 30°, whereas the methoxyl group stays nearly in the plane of the tetrazole ring. In consonance with the theoretical predictions, only one molecular species was experimentally observed in the as-deposited argon matrices. Theoretical calculations were also used to help in assignment of the experimental spectrum of the compound, the calculated spectrum showing a very good agreement with the experimental data. In situ UV-irradiation ([lambda] > 235 nm) of the matrix-isolated 5MPT induced unimolecular decomposition of the compound, which led mainly to production of methylcyanate and phenylazide, this latter further reacting to yield, as final product, 1-aza-1,2,4,6-cycloheptatetraene. 3-Methoxy-1-phenyl-1H-diazirene was also observed experimentally as minor product, resulting from direct elimination of molecular nitrogen from 5MPT.