In anaerobic and nonaq. system, the cluster [Mo2Fe2S4(S2CNEt2)5].MeCN (I) was prepared from (NH4)2MoS4, FeCl3 and NaS2CNEt2. I contains a [Mo2Fe2S4]5+ cubane-like core with a chelating ligand S2CNEt2 per metal atom, and both Mo atoms are bridged by the 5th S2CNEt2 group. XPS and Moessbauer spectral study and comparison of M-S (M = Fe or Mo) bond lengths show that both Fe atoms display different oxidation states, but both Mo atoms have the same oxidation state. The compound is paramagnetic matter, mm = 4.27 mB. In addition, IR, UV-visible spectra and catalytic activity of I in C2H2 reduction were also determine I is monoclinic, space group P21/c, a 19.397(7), b 10.891(7), c 24.302(8) ? b 108.95(2)? dc = 1.66 g cm-3, Z = 4, R = 0.045, Rw = 0.036.

Key words: ULTRAVIOLET SPECTROPHOTOMETRY, CRYSTAL STRUCTURE DETERMINATION, INFRARED SPECTROPHOTOMETRY, IRON COMPLEX, MAGNETIC PERMEABILITY, MOLYBDENUM COMPLEX, X-RAY PHOTOELECTRON SPECTROMETRY, OXIDATION STATE, CLUSTER COMPOUND, SULFIDE COMPLEX