Abstract: The data of electronic and infrared spectra are reported for the following four Fe4S₄clusters: (Ⅰ) [Et₄N][Fe₄S₄(Et₂dtc)₄], (Ⅱ) [Et₄N],[Fe₄S₄(Et₂dtc)₄], (Ⅲ)[Et₄N]₃[Fe₄S₄(Et₂dtc)₄],(W)[Bu₄N]₂[Fe₄S₄(Ph-S)₄]. According to the weak-ligand-field theory and the structure informations provided by X-ray diffraction, all the spectra were analyzed, assigned and listed in this paper. Comparing the individual spectra with each other, the following regulations can be drawn: (1) If the geometric structures of coordination anions are the same, the change of valence state of the central ion causes the apparent shifts of d-d bands in the electronic spectra and maintains infrared spectra principally. (2) In the coordination anions, the increase of oxidation state of the central ion results in the red-shift of M←L charge transfer bands. (3) If electron-pushing ability of the groups connected with the coordinating atom increases, the vibration bands of M-L bond move to the higher frequencies. These regulations above just show that our assignment to the spectra is reasonable.

Key words: Fe₄S₄cluster, Cubane-like, Analysis and assignment of spectra