Investigations on the Synthesis, Structural Characterization, and Crystal Structures of Three Diiron and Tetrairon Azadithiolate Complexes

Three diiron and tetrairon azadithiolate complexes as models for the active site of [FeFe] hydrogenase were prepared. Reaction of complex Fe 2 (SCH 2 OH) 2 (CO) 6 and NH 2 CH 2 CH 2 CH 2 OCH 3 resulted in the diiron azadithiolate hexcarbonyl complex Fe 2 [(SCH 2 ) 2 NCH 2 CH 2 CH 2 OCH 3 ](CO) 6 ( 1 ) in moderate yield. Furthermore, treatment of complex 1 with mono phosphine ligand PPh 3 and diphosphine ligand Ph 2 PCH 2 CH 2 PPh 2 in the presence of decarbonylation reagent Me 3 NO · 2H 2 O yielded the phosphine‐substituted azadithiolate complexes Fe 2 [(SCH 2 ) 2 NCH 2 CH 2 CH 2 OCH 3 ]CO) 5 (PPh 3 ) ( 2 ) and {Fe 2 [(SCH 2 ) 2 NCH 2 CH 2 CH 2 OCH 3 ](CO) 5 } 2 (Ph 2 PCH 2 CH 2 PPh 2 ) ( 3 ) respectively. The new complexes 1 – 3 were fully characterized by elemental analysis, IR, 1 H, 13 C, 31 P NMR spectroscopy and X‐ray crystallography. It is worthy to note that the crystallographic studies show the unusual difference of the methoxypropanyl substituent on the N atom of complexes 1 and 2 , largely because of the affection of phosphine ligand PPh 3 . In addition, complex 1 was found to be a catalyst for H 2 production under electrochemical condition.