The IR spectra of some linear Mo-Fe-S clusters [Cl2FeS2MoS2FeCl2]2-, [S2MoS2FeCl2]2-, [S2MoS2Fe(SPh)2]2-, [S2MoS2FeS2Fe(SPh)2]3-, [S2MoS2FeS2.MoS2]3-, [Cl2FeS2FeCl2]2-, and [(PhS)2FeS2Fe(SPh)2]2- were investigated. The characteristic frequencies nMo-St, nMo-Sb, nFe-Sb, nFe-SPh, nFe-Cl were assigned by comparing their vibrational frequencies, structural parameters and oxidation states of metal in these clusters. The assignment of dS-Mo-S was attempted. The influence of Mo atom on nFe-Sb in the clusters containing the heteronuclear MoS2Fe unit and the electrophilic induced effect in a different way are discussed. The internal relationship and regularity between the characteristic frequencies and some structural parameters were demonstrated. Finally a valuable parameter Dn, which may be taken as a qual. estimate of the extent of Fe ?Mo charge transfer in Mo-Fe-S clusters, is proposed.

Key words: STRUCTURE PARAMETER, INFRARED SPECTROPHOTOMETRY, IRON COMPLEX, NITROGENASE, BIOLOGICAL NITROGEN FIXATION, MOLYBDENUM COMPLEX, DISULFIDE, OXIDATION STATE, CLUSTER COMPOUND, SULFIDE COMPLEX