Azadithiolates cofactor of the iron-only hydrogenase and its PR3-monosubstituted derivatives : Synthesis, structure, electrochemistry and protonation

The core structure (mu-SCH2)(2)NH[Fe-2(CO)(6)](5) of Fe-only hydrogenases active site model has been synthesized by the condensation of iron carbonyl sulfides, formaldehyde and silyl protected amine. Its monosubstituted complexes (mu-SCH2)(2)NH[Fe-2(CO)(5)PR3] (R = Ph (6), Me (7)) were accordingly prepared. The coordination configurations of 5 and 6 were characterized by X-ray crystallography. Protonation of complex 7 to form the N-protonated product occurs in an acetonitrile solution upon addition of triflic acid. The redox properties of these model complexes were studied by cyclic voltammetry. (C) 2007 Elsevier B.V. All rights reserved.