INTRODUCTION. In the study of nitrogenases, scientists have proposed many models for the active center of MoFe protein and for FeMoco. All of them contain a basic structural unit [FeS_2M] (M=Fe or Mo). We have reported some structural regularities in a series of linear Mo-Fe-S compounds. In order to investigate the electron distribution and the synergism of metal atoms within a Mo-Fe-S cluster with [MoFe_3S_4] cubane unit, we have synthe INTRODUCTION. In the study of nitrogenases, scientists have proposed many models for the active center of MoFe protein and for FeMoco. All of them contain a basic structural unit [FeS_2M] (M = Fe or Mo). a series of linear Mo-Fe-S compounds. In order to investigate the electron distribution and the synergism of metal atoms within a Mo-Fe-S cluster with [MoFe_3S_4] cubane unit, we have synthe