INVESTIGADORES
GOMEZ ZAVAGLIA Andrea
artículos
Título:
Matrix Isolation FTIR, Theoretical Structural Analysis and Reactivity of Amino-Saccharins: N-(1,1-Dioxo-1,2-Benzisothiazol-3-yl)- N-Methyl Amine and N-(1,1-Dioxo-1,2-Benzisothiazol-3-yl)-N,N-Dimethylamine
Autor/es:
R. ALMEIDA, A. GÓMEZ-ZAVAGLIA, A. KACZOR, A. ISMAEL, M.L.S. CRISTIANO, R. FAUSTO
Revista:
JOURNAL OF MOLECULAR STRUCTURE
Editorial:
Elsevier
Referencias:
Lugar: Amsterdam; Año: 2009 vol. 938 p. 198 - 206
ISSN:
0022-2860
Resumen:
In this work, two novel amino-substituted derivatives of saccharin, N-(1,1-dioxo-1,2-benzisothiazol-3-
yl)-N-methyl amine (MBAD) and N-(1,1-dioxo-1,2-benzisothiazol-3-yl)-N,N-dimethyl amine (DMBAD),
were synthesized and characterized, and their molecular structure and vibrational properties were investigated
by matrix-isolation FTIR spectroscopy and theoretical calculations undertaken using different levels
of approximation. The calculations predicted the existence of two conformers of MBAD. The lowest
energy form was predicted to be considerably more stable than the second conformer (DE > ca.
20 kJ mol1) and was the sole form contributing to the infrared spectrum of the compound isolated in
solid xenon. Both conformers have planar amine moieties. In the case of DMBAD, only one doubly-degenerated-
by-symmetry conformer exists, with the amine nitrogen atom considerably pyramidalized. The
effect of the electron-withdrawing saccharyl ring on the CN bond lengths is discussed. The different
structural preferences around the amine nitrogen atom in the two molecules were explained in terms
of repulsive interactions involving the additional methyl group of DMBAD. Observed structural features
are correlated with the reactivity exhibited by the two compounds towards nucleophiles. The experimentally
obtained spectra of the matrix-isolated monomers of MBAD and DMBAD were fully assigned by
comparison with the corresponding calculated spectra.