Investigation of amino acid containing [FeFe] hydrogenase models concerning pendant base effects

The present investigations deal with the modeling of the peptide surrounding of [FeFe] hydrogenase using amine containing disulphides to simulate possible influences of the amino acid lysine (K237) on the electrochemical and electrocatalytic properties of biomimetic compounds based on [Fe2S2] moieties. Fe-3(CO)(12) was reacted with Boc-4-amino-1,2-dithiolane, Boc-Adt-OMe (Adt = 4-amino-1,2-dithiolane-4-carboxylic acid, Boc = tert-butoxycarbonyl) and Boc-Adp tert-butyl ester (Adp = (S)-2-amino-3-(1,2-dithiolan-4-yl)propionic acid) to elongate the Fe center dot center dot center dot N distance in comparison to the well known [Fe-2{(SCH2)(2)NR}(CO)(6)] model complexes. Efforts to deprotect the complexes containing Boc-4-amino-1,2-dithiolane with trifluoroacetic acid result in the formation of [Fe-3(mu(3)-O)(mu-O2C2F3)(6)(OC4H8)(2)(H2O)]. The novel [2Fe(2)S] complexes are characterized using spectroscopic, electrochemical techniques and X-ray diffraction studies. (C) 2009 Elsevier Inc. All rights reserved.