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

Abstract

A series of N-functionalized diiron azadithiolate complexes, [(µ-SCH₂)₂NCH₂CO₂Me]Fe₂(CO)₅L [L = CO (1); PPh₃ (2); Ph₂PCH₂PPh₂ (3)], as active site models of [FeFe]-hydrogenases has been prepared and characterized. While 1 was prepared by a sequential reaction of (µ-HS)₂Fe₂(CO)₆ with two equiv. of aqueous HCHO, followed by treatment of (µ-HOCH₂S)₂Fe₂(CO)₆ with one equiv. of H₂NCH₂CO₂Me in 46% yield; 2 and 3 were prepared by a carbonyl substitution reaction of 1 with PPh₃ or Ph₂PCH₂PPh₂ in the presence of Me₃NO · 2H₂O 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 PPh₃ ligand resides in an axial position of the square pyramid of Fe2.

Keywords:

• Diiron azadithiolate
• [FeFe]-hydrogenases
• Synthesis
• Crystal structure

Acknowledgments

This work was supported by the start-up foundation of Ningbo University of Technology, the National Natural Science Foundation of China (20902051), Foundation of the Education Committee of Zhejiang Province (Z200906833), and Ningbo Natural Science Foundation (2010A610186).