Figure 2.

Changes in the absorption spectra associated with the reaction of 3–Sc (0.34 mM) with ferrocene (30 equiv.) at −90 °C. Inset: Absorption spectra of 2 (dotted line) (0.36 mM) and its reaction product (solid line) with ferrocene (30 equiv.) in presence of 1 equivalent of Sc(OTf)₃ at −90 °C. The yield of the ferrocenium was determined on the basis of the known extinction coefficient (ε) of 620 nm band = 505 M⁻¹cm⁻¹ in CH₂Cl₂ at −90 °C.