Fig. 2. TA and characterization of e^–/H⁺ CSSs.

For 1 in CH₂Cl₂, global fitting of the time evolution of the visible (A) and mid-IR (C) TA spectra give the evolution-associated visible spectra (B) and mid-IR spectra (D) of the LES and CSS. In CH₂Cl₂ (but not in other solvents), there is a small contribution of a longer-lived transient. Arrows in (A) to (D) indicate spectral changes between the LES and CSS. In (E to H), time traces (circles) and fits from global analysis (lines) show the KIE for CS and CR of 1 in CH₂Cl₂ (E), the solvent polarity effect on CR time constants for 1 (F), and the relative CR time constants for 1 to 3 in CH₂Cl₂ (G) and DMF (H). For (F) to (H), the time traces are at wavelengths for isosbestic points for the LES and CSS spectra, so the traces only show the CSS→GS (CR) reaction in CH₂Cl₂ (at 533 nm) and n-BuCN and DMF (at 550 nm).