Novel carbonyl dithiolate diiron complexes [Fe 2 (CO) 6-x L x (µ-dithiolate)] (x = 3, 4), related to the active site of [FeFe]-hydrogenases, have been synthesized by photolysis of hexacarbonyl species [Fe 2 (CO) 6 (µ-dithiolate)] (dithiolate = {S 2 (CH 2 ) 3 } (pdt), {SCH 2 } 2 NR with R = i Pr (adt i-Pr ) or Bn (adt Bn )). The new compounds were characterized by structural and spectroscopic methods. Variable-temperature (VT) NMR experiments revealed their fluxionality in solution depending on terminal ligands exchanges and dithiolate bridge motions. Preliminary results on their protonation giving hydride species and their electrochemical properties are reported.