Design and Structural Characterization of Ferrocenyl Bithiophene Thioketone-Based Iron Complexes

The exceptional catalytic efficiency of [FeFe]-hydrogenases has driven intense efforts to reproduce their structure and function in synthetic models. A key structural feature governing the behavior of synthetic H-cluster analogs lies in the identity of the bridging dithiolato ligands that link the iron centers. These ligands play a pivotal role in tuning the electron density of the metal core, thereby dictating the complex’s redox characteristics and catalytic reactivity. In this context, we herein describe the synthesis and application of ferrocenyl bithiophene-2,2′-yl thioketone (1) as a proligand for assembling biomimetic models of the [FeFe]-hydrogenase active site. The obtained complexes were thoroughly examined using a suite of analytical methods, including NMR and IR spectroscopy, elemental analysis, and a single-crystal X-ray diffraction, affording comprehensive structural and chemical characterization. Furthermore, their electrochemical behavior toward proton reduction and hydrogen evolution was evaluated via cyclic voltammetry, enabling direct comparison with structurally related analogs.