Evidence of IR-Induced Chemistry in a Neat Solid: Tautomerization of Thiotropolone by Thermal, Electronic, and Vibrational Excitations

Thiotropolone isolated in argon and xenon matrices (as monomers) or a neat solid the crystalline amorphous state) at low temperature was found to exist only thione-enol form. Visible light irradiation (λ ≥ 400 nm) leads → thiol-keto tautomerization under conditions 15 K. The assignment of IR spectra two thiotropolone tautomers (thione-enol thiol-keto) carried out with support B3LYP/6-311+G(2d,p) computations. form generated situ tautomerize back upon annealing up 100 Gaussian-4 (G4) computations estimate that such process has an energy barrier ∼25 kJ mol–1, which is consistent observations. Moreover, it narrowband solid, frequency its CH stretching overtones/combination modes, also induces Such result constitutes important demonstration vibrationally induced chemistry conditions.