Unexpectedly, a class of Fe-S complexes containing a bridging vinylidene acetate ligand, i.e. (s,p-m-CH3CO2C:CH2)(m-RS)Fe2(CO)6 (I, R = Et, Me3C, Ph), were prepared by reaction of acetyl chloride with an active salt of [(m-CO)(m-RS)Fe2(CO)6]Et3NH formed from Fe3(CO)12, RSH, and Et3N. The structures and conformations of these complexes were characterized by elemental anal., IR, 1H NMR, and x-ray diffraction techniques and the mechanism of their formation was discussed briefly. The crystal structure of I (R = Ph) was determine A kind of s-interaction occurs between the carbon atom bearing the acetate group and one iron atom whereas a p-interaction occurs between carbon-carbon double bond and another iron atom. The Fe-Fe bond length is 2.553(1) ?

Key words: CRYSTAL STRUCTURE DETERMINATION, REACTION MECHANISM, INFRARED SPECTROPHOTOMETRY, X-RAY DIFFRACTION ANALYSIS, IRON COMPLEX, ACYL CHLORIDES, PROTON MAGNETIC RESONANCE SPECTROMETRY, PROTON MAGNETIC RESONANCE SPECTROMETRY, ACETIC ACID ETHENYL ESTER, SULFIDE COMPLEX