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(mu-SCH2)2]Fe-2(CO)(6), one being amino protected [N(CH2CH2NHTs)(mu-SCH2)(2)]Fe-2(CO)(6) (8) and the other [(mu-SCH2)(2)Fe-2(-CO)(6)NCH2CH2N (mu-SCH2)(2)]Fe-2(CO)(6) (9) are described. These two complexes are readily prepared in a S(N)2 manner between double lithium anion and bis(chloromethyl) amine derivatives. The structures of 8 and 9 were characterized by IR, H-1, C-13 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. (c) 2005 Elsevier B.V. All rights reserved.