A Dinucleating Ligand System with Varying Terminal Donors to Mimic Diiron Active Sites
Stephan Walleck, Thorsten Glaser
Abstract
Abstract To mimic dinuclear active sites of metalloproteins, we have developed a dinucleating ligand system consisting of two tetradentate tripodal ligand compartments with varying terminal donors (carboxylates, phenolates, and pyridines). These ligands provide access to a series of μ ‐oxo‐bridged diferric complexes. The spectroscopic study allows to investigate the molecular structures even in solution, e. g . depending on protonation/deprotonation of coordinated OH − and H 2 O ligands or to observe a reversible pH‐dependent carboxylate‐shift between terminal and bridging binding mode. The electrochemical behavior is strongly influenced by the exogenous ligands, e. g . OH − facilitates oxidation to Fe IV by 690 mV relative to Cl − . Using the terminal carboxylates and a {Fe III ( μ ‐O) 2 Fe III } core even allows oxidation with O 2 to a high‐valent species with Fe IV ( S =2). The implications of this study for further generation of high‐valent or peroxo species and their utilization in catalysis is discussed.