IntroductionThe synthetic analogues of 1-Fe,2-Fe and 4-Fe active sites for iron-sulfur proteinshave been subjected to much experimental studies.Evidences indicate that the modelcomplexes Fe_2S_2(SR)_2~(2-) and Fe_4S_4(SR)_4~(2-)(with R=alkyl and aryl)are apt to undergo substitu-tion at terminal sites rather than reacting via the core Fe_2S_2 or Fe_4S_4.However,dianionsFe_2S_2.(SR)_4~(2-) are electrochemically reducible to trianions Fe_2S_2(SR)_4~(3-) which can rapidlydimerize to 4-Fe species Introduction The synthetic analogues of 1-Fe, 2-Fe and 4-Fe active sites for iron-sulfur proteins have been subjected to much experimental studies. Evidences that that model complexes Fe2S_2 (SR) _2 2- and Fe_4S_4 (SR) (2-) (with R = alkyl and aryl) are apt to undergo substitu tion at terminal sites rather than via via the core Fe_2S_2 or Fe_4S_4.However, dianionsFe_2S_2. (SR) _4 ~ (2-) are electrochemically reducible to trianions Fe_2S_2 (SR) _4 ~ (3-) which can rapidly dieimeze to 4-Fe species