4Fe-4S ferredoxin model complexes, [NEt4]2[Fe4S4(Z-cys-Ile-Ala-OMe)4], [N(n-Bu)4]2[Fe4S4(2,4,6-trimethylbenezenethiolato)4], and [NMe4]2[Fe4S4(2,4,6-triisopropylbenzenethiolato)4] having highly sterically hindered ligands exhibit an electrochemically quasi-reversible redox couple of 2-/1- at +0.12 V, +0.02 V, and −0.03 V vs. SCE, respectively, but an irreversible redox couple of 3-/2-. The results suggest that [Fe4S4(SR)4]1− is stabilized with protection by hydrophobic bulkiness, but that [Fe4S4(SR)4]3− is destabilized by the bulkiness.

[Me4N]2[Fe4S4(S‐tBu)4] reagiert mit den entsprechenden Peptiden zu den als Modelle von P. aerogenes Fd.

The complexes (I) are synthesized from (NEt4)2[Fe4S4(S‐ tBu)4] by ligand exchange as [4Fe‐4S] ferredoxin model complexes having an invariant sequence of Cys‐X‐Y‐Cys (X, Y: amino acid residues) of bacterial ferredoxins.