are molecular ensembles of iron
. They are most often discussed in the context of the biological role for iron-sulfur protein
s, which are pervasive.S. J. Lippard, J. M. Berg “Principles of Bioinorganic Chemistry” University Science Books: Mill Valley, CA; 1994. . Many Fe-S clusters are known in the area of organometallic chemistry
and as precursors to synthetic analogues of the biological clusters (see Figure).
The most well characterized clusters have the formula Fe4S4(SR)4
2-, which are known for many R substituents, and with many cations. Many variations have been prepared including the incomplete cubanes Fe3S4(SR)3
Organometallic Fe-S clusters include the sulfido carbonyls with the formula Fe2S2(CO)6, H2Fe3S(CO)9, and Fe3S2(CO)9. Compounds are also known that incorporate cyclopentadienyl ligands, such as (C5H5)4Fe4S4.