Bridging methylene addition to the disulfur ligands of an iron-sulfur cluster compound. X-ray structure of [Fe4(.mu.3-S)2((.mu.3-S2)CH2(.mu.3-S2))(C5H4Me)4]2+ (FeCl4)2-

The nucleophilic sulfur atoms of the disulfur ligands in Fe 4 S 6 (C 5 H 4 R) 4 (1) (R=H, Me) react easily with the alkyl halides CH 2 X 2 (X=Cl, I) or CH 3 I, to give the title cluster compounds