title: Photoinduced amino-imino tautomerism: an infrared study of 2-amino-5-methylpyridine in a low-temperature argon matrix.
abstract: The photoreaction of 2-amino-5-methylpyridine was investigated by matrix-isolation infrared spectroscopy and DFT calculation. Photoinduced reversible amino (N=C-NH(2))-imino (NH-C=NH) tautomerism was found between 2-amino-5-methylpyridine and 5-methyl-2(1H)-pyridinimine; the amino tautomer changes to the imino tautomer by UV irradiation (340>lambda>or= 300 nm) and the reverse change occurs by longer-wavelength light irradiation (420>lambda>or= 340 nm). The results of the CASSCF calculation revealed that the amino-imino tautomerism proceeds in vibrational relaxation process from electronic excited state to the ground state. The IR spectra of 2-amino-5-methylpyridine in the T(1) state and 5-methyl-2-pyridinamino radical were also obtained by UV irradiation (lambda>or= 300 nm).
authors: Center for Quantum Life Sciences, Hiroshima University, 1-3-1, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan. rosso@hiroshima-u.ac.jp
authors: Nobuyuki
authors: N
authors: Akai
authors: Takanori
authors: T
authors: Harada
authors: Kei
authors: K
authors: Shin-Ya
authors: Keiichi
authors: K
authors: Ohno
authors: Misako
authors: M
authors: Aida