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 Fecdots, three dots, centeredN distance in comparison to the well known [Fe(2){(SCH(2))(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-O(2)C(2)F(3))(6)(OC(4)H(8))(2)(H(2)O)]. The novel [2Fe2S] complexes are characterized using spectroscopic, electrochemical techniques and X-ray diffraction studies.