Diiron model complexes (μ-pdt) Fe2 (CO) 5L with L= pyridine ligands, eg py (A), etpy (B), btpy (C), were synthesized as active site analogues of [FeFe] hydrogenase, and characterized by X-ray crystallography and electrochemistry. Pyridine-N ligation was found to be able to tune the redox properties of the diiron centers of model complexes.