Philippine Science Letters
vol. 5 | no. 2 | 2012
published online December 7, 2012


Towards biologically inspired fuelcell electrocatalysts: electrochemistry of a diiron hydrogenase mimic

by Jean Sanabria-Chinchilla, Tianbiao Liu, Christine M. Thomas, Brett Savoie, Marcetta Y. Darensbourg and Manuel P. Soriaga*

Department of Chemistry, Texas A&M University, College Station, TX 77843



We have a long-standing interest in the electrochemical characterization of synthetic analogues of hydrogenase biocatalysts, with the ultimate goal of parlaying the information towards the modification of the surfaces of inexpensive electrodes by the immobilization of homogeneous catalysts for H2 production and/or uptake. The initial stage of the study is focused on the synthesis of suitably ligated base metals or metal complexes with hydrogenase-like functional activity followed by the assessment of their electrochemical activities. In this regard, N-heterocyclic carbene (NHC) ligands have taken on remarkable roles, because of their unique steric and electronic properties, in organometallic chemistry and homogeneous catalysis. They are now also exploited as candidates in synthetic analogues of bioorganometallic enzymes as in the [FeFe]- hydrogenase active site. In the present paper, we contrast the electrochemical behaviors of the complex (µ-pdt)[Fe(CO)3] [Fe(CO)2IMes] with the saturated analogue, SIMes (SIMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidine) in the (µ-pdt) [Fe(CO)3][Fe(CO)2(SIMes)] complex, and with the protonated imidazolium salts that are precursors of the NHC ligands, HNHC+ Cl-. Our goal was to further confirm and gain insight into the nature of the 2-electron process of (µ-pdt)[Fe(CO)3] [Fe(CO)2IMes] as well as to establish the extent to which the NHC ligands are involved with respect to the overall electron uptake by the complexes.

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Submitted: August 7, 2012
Revised: September 6, 2012
Accepted: September 27, 2012
Published: December 7, 2012
Editor-in-charge: Gisela P. Padilla - Concepcion
Nikola Batina
Carlos Cabrera
Ghezai Musie