Molecular Structure, Vibrational Spectra and Photochemistry of 5-Mercapto-1-Methyltetrazole

GOMEZ ZAVAGLIA, ANDREA, I. REVA, L. FRIJA, M.L.CRISTIANO Y R. FAUSTO

Funchal, Madeira

Congreso; Matrix-Isolation Spectroscopy 2005 (MATRIX 2005); 2005

Grupo de Espectroscopia a Bajas Temperaturas. Universidad de Coimbra

  Molecular Structure, Vibrational Spectra and Photochemistry of 5-Mercapto-1-Methyltetrazole in solid Argon   A. Gómez-Zavaglia1,2, I. D. Reva1, L. Frija3, M. L. Cristiano3 and R. Fausto1 1 Department of Chemistry. University of Coimbra, Portugal (3004-535). 2 Facultad de Farmacia y Bioquímica. Universidad de Buenos Aires, Argentina (CP 1113) 3 Department of Chemistry and Biochemistry. University of Algarve, Faro, Portugal (8005-139) angoza@qui.uc.pt   In this work, 5-mercapto-1-methyltetrazole (MTT) was studied by matrix-isolation and low temperature solid-state infrared spectroscopy, DFT(B3LYP)/6-311++G(d,p) calculations and photochemical methods. In the low temperature neat solid phase and isolated in an argon matrix, MTT was found to exist in the 1-methyl-1,4-dihydro-5H-tetrazole-5-thione tautomeric form. The infrared spectra of the compound were fully assigned and correlated with structural properties. In situ UV-irradiation (l > 235 nm) of the matrix-isolated monomer of MTT is shown to trigger different photochemical processes, all of them involving cleavage of the tetrazole ring: e.g., (1) nitrogen loosing, with production of 1-methyl-1H-diazirene-3-thiol, which is produced in two different conformers; (2) ring cleavage leading to production of methyl isothiocyanate and azide; (3) simultaneous elimination of nitrogen and sulphur with production of 1-methyl-1H-diazirene. Following these photoprocesses, subsequent reactions occur, leading to production of methyldiazene, carbon monosulphide and nitrogen hydride. Spectroscopic evidence of the production of the above mentioned chemical species is provided.