Neodymium(III) Complexes Capable of Multi‐Electron Redox Chemistry

A family of neodymium complexes featuring a redox‐active ligand in three different oxidation states has been synthesized, including the iminoquinone (L⁰) derivative, (^dippiq)₂NdI₃ ( 1‐iq ), the iminosemiquinone (L¹⁻) compound, (^dippisq)₂NdI(THF) ( 1‐isq ), and the amidophenolate (L²⁻) [K(THF)₂][(^dippap)₂Nd(THF)₂] ( 1‐ap ) and [K(18‐crown‐6)][(^dippap)₂Nd(THF)₂] ( 1‐ap crown ) species. Full spectroscopic and structural characterization of each derivative established the +3 neodymium oxidation state with redox chemistry occurring at the ligand rather than the neodymium center. Oxidation with elemental chalcogens showed the reversible nature of the ligand‐mediated reduction process, forming the iminosemiquinone metallocycles, [K(18‐crown‐6)][(^dippisq)₂Nd(S₅)] ( 2‐isq crown ) and [K(18‐crown‐6)(THF)][(^dippisq)₂Nd(Se₅)] ( 3‐isq crown ), which are characterized to contain a 6‐membered twist‐boat ring.