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. Fe₃(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 FeN distance in comparison to the well known Fe₂{(SCH₂)₂NR}(CO)₆] model complexes. Efforts to deprotect the complexes containing Boc-4-amino-1,2-dithiolane with trifluoroacetic acid result in the formation of Fe₃(μ³-O)(μ-O₂C₂F₃)₆(OC₄H₈)₂(H₂O)]. The novel 2Fe2S] complexes are characterized using spectroscopic, electrochemical techniques and X-ray diffraction studies.