The synthesis and characterization of iron-sulfur clusters stabilized by dimethylsilyl-bridged cyclopentadienyl groups are reported. The thermal reaction of Me2Si(eta(5)-C5H4)(2)Fe-2(CO)(4) (1) with S-8 yields the tetranuclear cubane-type cluster compound [Me2Si(eta(5)-C5H4)(2)](2)Fe4S6 (4) and the pentanuclear cluster compound [Me2Si(eta(5)-C5H4)(2)](2)-Fe5S12 (3) in high yields. The photochemical reaction of 1 with S-8 yields the tetranuclear cluster compound [Me2Si(eta(5)-C5H4)(2)](2)Fe4S6(CO) (5), which contains one residual terminal carbonyl. The crystal structures of 3 and 4 have been determined. Crystal data : 3 . CH2Cl2, monoclinic, C2/c, a = 23.480(13) Angstrom, b = 11.192 (4) Angstrom, c = 17.84(3) Angstrom, beta = 118.58(9)degrees, V = 4118(7) Angstrom(3), Z = 4, R = 0.078; 4, triclinic, , a = 8.4787(7) Angstrom, b = 12.9648(9) Angstrom, c = 13.4990(9) Angstrom, alpha = 79.857(8)degrees, beta = 75.293(8)degrees, gamma = 74.041(11)degrees, V = 1370.9(2) Angstrom(3), Z = 2, R = 0.0447. The F5S12 core of 3 has a bowtie Structure in which a central iron atom is octahedrally coordinated by six sulfur atoms from one tetrasulfido and four disulfido groups. The structure of 4 resembles the structure of the known iron-sulfur cluster Cp4Fe4S6. However, 4 shows a markedly enhanced thermal stability compared to Cp4Fe4S6. In their cyclic voltammograms, 4 and 5 exhibit electrochemical behavior typical of cubane-type Cp-iron-sulfur clusters, whereas the cyclic voltammogram of 3 is quite different. The v(CO) mode of 5 has been measured for four different oxidation states of the cluster by means of IR spectroelectrochemical methods. The Mossbauer spectra of 3 and 3(+) are in accordance with their pentanuclear structure.