A convenient ligand exchange pathway to [2Fe-2S] ferredoxin analogues.

The benzanellated analogues (NEt(4))(2)[Fe(2)S(2)(indolate)(4)] (2) and (NEt(4))(2)[Fe(2)S(2)(carbazolate)(4)] (3) of the previously reported parent (NEt(4))(2)[Fe(2)S(2)(pyrrolate)(4)] cluster (1) were synthesized and characterized spectroscopically. In contrast to 1 and 3, compound 2 can be applied as a versatile precursor in ligand exchange reactions with various thiophenols affording the thiophenolate-coordinate [2Fe-2S] clusters. Heteroaromatic thiols and chelating biphenols are suitable substrates in this conversion as well, providing a convenient access to a variety of new [2Fe-2S] ferredoxin analogues and related complexes. Several new S- and O-coordinate [2Fe-2S] clusters have been prepared and fully characterized, including five X-ray crystal structures.