(A) Mayer bond orders for Fe–O, O–O, Cu–O, OCu–H, and OPh–H. Population densities for (B) α-spin and (C) β-spin Fe dπ orbitals, O–O σ*, and PhO− HOMO correlated to O–O distance over the IRC. The Fe dπ orbitals are differentiated by their overlap with the peroxo MOs. O–O σ* orbital occupancy is only reported up to ∼40% occupation. The vertical dashed lines mark the O–O distance in TSPI.