Time dependent evolution of visible-NIR spectra for decomposition of the alkylperoxoiron(III) intermediates supported by β-BPMCN to oxoiron(IV) in CH3CN/H2O at 228 K (A; [FeII]0 = 0.58 mM, [tBuOOH]0 = 1.2 mM, [H2O] = 0.3 M), and to alkylperoxoiron(IV) in CH2Cl2 at 206 K (B; [FeII]0 = 1.8 mM, [tBuOOH]0 = 9.0 mM), as monitored by visible-NIR spectroscopy.