Magnetic studies of the high-potential protein model [Fe4S4(S-2,4,6-(iso-Pr)3C6H2)4]- in the [Fe4S4]3+ oxidized state

The magnetic susceptibility of the title compound has been examined over the 5-320 K temperature range. The results have been analyzed by use of a spin-system Hamiltonian that includes two Heisenberg AF coupling parameters, J 12 =J+ΔJ 12 and J 34 =J+ΔJ 34 , for the ferric (β) pair and the mixed-valence (α) pair, respectively, and one resonance delocalization parameter B for the α pair