Arynylmagnesium bromides cleave the S-S bond of μ-S_2Fe_2(CO)_6 to give equilibrium mixtures of “open” intermediates (μ-ArCS) (μ-BrMgS)Fe_2(CO)_6 and “closed” intermediates μ-[S(Ar)C=C(MgBr)S]Fe_2(CO)_6. The mixtures were treated with CpFe(CO)_2I or some of organic halides to yield corresponding “open” Fe-S complexes, whereas with CF_3CO_2H, gaseous HBr or CH_3HgCl to afford the “closed” ones. The “closed” products were also observed with those alkyl halides which eliminate HX easily. So, this kind of alkyl halides possibly functions as substrates through elimination of HX in reaction courses. Arynylmagnesium bromides cleave the SS bond of μ-S_2Fe_2 (CO) _6 to give equilibrium mixtures of “open ” intermediates (μ-ArCS) (μ-BrMgS) Fe_2 (CO) _6 and “closed ” intermediates μ- [ The mixtures were treated with CpFe (CO) _2I or some of organic halides to yield corresponding “open ” Fe-S complexes, with CF_3CO_2H, gaseous HBr or CH_3HgCl to afford the “closed ” ones. The “closed ” products were also observed with those alkyl halides which eliminate HX easily. So, this kind of alkyl halides possibly functions as substrates through elimination of HX in reaction courses.