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 (L ) derivative, ( iq) NdI (1-iq), the iminosemiquinone (L ) compound, ( isq) NdI(THF) (1-isq), and the amidophenolate (L ) [K(THF) ][( ap) Nd(THF) ] (1-ap) and [K(18-crown-6)][( ap) Nd(THF) ] (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)][( isq) Nd(S )] (2-isq crown) and [K(18-crown-6)(THF)][( isq) Nd(Se )] (3-isq crown), which are characterized to contain a 6-membered twist-boat ring.