Electrocatalysis of hydrogen production by active site analogues of the iron hydrogenase enzyme: structure/function relationships
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A series of binuclear Fe I Fe I complexes, (μ-SEt) 2 [Fe(CO) 2 L] 2 (L = CO (1), PMe 3 (1-P)), (μ-SRS)[Fe(CO) 2 L] 2 (R = CH 2 CH 2 (μ-edt): L = CO (2), PMe 3 (2-P) R = CH 2 CH 2 CH 2 (μ-pdt): L = CO (3), PMe 3 (3-P) and R = o-CH 2 C 6 H 4 CH 2 (μ-o-xyldt): L = CO (4), PMe 3 (4-P)), that serve as structural models for the active site of Fe-hydrogenase are shown to be electrocatalysts for H 2 production in the presence of acetic acid in acetonitrile. The redox levels for H 2 production were established by spectroelectrochemistry to be Fe 0 Fe 0 for the all-CO complexes and Fe I Fe 0 for the PMe 3 -substituted derivatives. As electrocatalysts, the PMe 3 derivatives are more stable and more sensitive to acid concentration than the all-CO complexes. The electrocatalysis is initiated by electrochemical reduction of these diiron complexes, which subsequently, under weak acid conditions, undergo protonation of the reduced iron center to produce H 2 . An (η 2 -H 2 )Fe II –Fe 0/I intermediate is suggested and probable electrochemical mechanisms are discussed. © 2003 The Royal Society of Chemistry.
author list (cited authors)
Chong, D., Georgakaki, I. P., Mejia-Rodriguez, R., Sanabria-Chinchilla, J., Soriaga, M. P., & Darensbourg, M. Y.