Ferrocene-histidine conjugates: N-ferrocenoyl-histidyl(imN-ferrocenoyl)methylester: synthesis and structure

The preparation of the new ferrocenoyl histidyl conjugates N-Fc-His-OMe (2) and N-Fc-His(ε-N-Fc)-OMe (3) and of a simple ferrocenoyl imidazole conjugate Fc-Im (4) is reported together with their spectroscopic and electrochemical characterization. The electrochemistry of 3 exhibits two fully reversible one-electron oxidations, which are due to the stepwise oxidation of the two ferrocenoyl groups. The crystal structure of 3 shows the difference in the chemical environment of the two Fc groups, one being attached to the α-N and one being attached to the ε-N of the imidazole of histidine. There is no discernible intermolecular interaction present in the crystal structure.