4.2-K Mössbauer spectra of MnIV/FeIII-R2 derived by component analysis of the experimental spectra. The solid lines are simulations according to the spin Hamiltonian given in the Supporting Information and the following parameters: STotal = 1, DS=1 = −1.9 cm−1, (E/D)S=1 = 0.33, δ = 0.52 mm/s, ΔEQ = 1.32 mm/s, η = −2.6, (A/gNβN)Fe = (−40.2, −38.9, −38.0) T.