Synthesis, structures and electrochemical properties of amino-derivatives of diiron azadithiolates as active site models of Fe-only hydrogenase

The preparation and characterization of two novel amino-incorporated sulfur-bridged dinuclear iron (I) complexes of the type [NR(μ-SCH2)2]Fe2(CO)6, one being amino protected [N(CH2CH2NHTs)(μ-SCH2)2]Fe2(CO)6 (8) and the other [(μ- SCH2)2Fe2(CO)6NCH2CH2N (μ-SCH2)2]Fe2(CO)6 (9) are described. These two complexes are readily prepared in a SN2 manner between double lithium anion and bis(chloromethyl) amine derivatives. The structures of 8 and 9 were characterized by IR, 1H, 13C NMR, MS and HRMS spectra and further determined by X-ray analyses. Protonation of complex 8 gave the mono N-protonated product, while for 9 the protonation occurred in both of the N atoms. The redox properties were evaluated by cyclic voltammograms. It was shown that these two complexes can catalyze electrochemical reduction of proton to molecular hydrogen.

Graphical abstractThis paper describes the preparation of two novel amino-incorporated FeS complexes. Their structures are characterized by 1H, 13C NMR, MS, IR, and HRMS spectra and further determined by X-ray analysis. Their protonations and electrochemical properties showed that they are better catalyst for the reduction of proton to hydrogen than aromatic nitrogen atom bridged complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide