Synthesis, characterization, and crystal structures of N-functionalized diiron azadithiolate complexes related to the active site of [FeFe]-hydrogenases

摘要

A series of N-functionalized diiron azadithiolate complexes, [(μ-SCH_2)_2NCH_2CO_2Me] Fe_2(CO)_5L [L = CO (1); PPh_3 (2); Ph_2PCH_2PPh_2 (3)], as active site models of [FeFe]-hydrogenases has been prepared and characterized. While 1 was prepared by a sequential reaction of (n-HS)_2Fe_2(CO)_6 with two equiv. of aqueous HCHO, followed by treatment of (μ-HOCH_2S)_2Fe_2(CO)_6 with one equiv. of H_2NCH_2CO_2Me in 46% yield; 2 and 3 were prepared by a carbonyl substitution reaction of 1 with PPh_3 or Ph_2PCH_2PPh_2 in the presence of Me_3NO · 2H_2O in 90% and 85% yields, respectively. The crystal structures of 1 and 2 revealed that the substituent attached to the bridgehead nitrogen occupies an equatorial position and the PPh_3 ligand resides in an axial position of the square pyramid of Fe2.