INTRODUCTION. In the study of synthetic methods and chemical reactions of Mo-Fe-S cluster compounds for simulation of the catalytic active center of nitrogenase, the reaction.systems of MoS_4~(2-) and varios ferric or ferrous salts have caused the interests of many chemists. We have been studying the system of ferrous thiolates and thiomolybdates and found interesting results. In a previous paper, we reported the syn-