MP-5 (2.3 µmole) was dissolved in 600 µL of D2O:MeOD (1:1) (v/v). Iron triflate (4.6 µmole) was dissolved in 180 µL of deuterated solvent. Arrow indicates increase in the equivalents of metal added: 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, corresponding to the spectra labeled 1 to 10, respectively.