Neocuproine as a Redox-Active Ligand Platform on Iron and Cobalt

A family of bis(neocuproine) complexes of Fe²⁺ and Co²⁺ have been investigated for neocuproine redox noninnocence. A series of redox isomers of M(neocuproine)₂ (where n = 2, 1, 0 for Co and n = 2, 0 for Fe) have been synthesized and thoroughly characterized. The electronic structure of these complexes has been rigorously investigated using a variety of techniques, including X-ray absorption spectroscopy, Mössbauer spectroscopy, X-ray diffraction, electron paramagnetic resonance spectroscopy, and magnetic measurements. All of these techniques are consistent with ligand-based reduction events to generate radical neocuproine complexes. Thus, neocuproine adds to a growing family of chelating N-donor type ligands that participate in redox noninnocence and may be useful for future catalyst and reaction design.