Stabilising effects on the 4Fe-4S core analogues for high-potential iron-sulphur proteins with a hydrophobic environment provided by macrocycles

Studies of redox potentials and reactions with molecular oxygen of a series of 4Fe-4S complexes attached to a 36-membered macrocycle show that all three electron transfer processes, 1-/2-, 2-/3-, and 3-/4-, are reversible for the cyclic aryl-substituted clusters, and that half-wave potentials for alkyl derivatives with hydrophobic macrocycles showed largely positive shifts of the 1-/2- couples as given in high-potential iron-sulphur proteins as well as a stabilising effect of the cores towards molecular oxygen.