One- and Two-Electron Reduction of N-Heterocycles by Divalent Rare Earth Terphenyl Anilide Complexes

Complexes 1Y, 1La, 1Tm, and 1Lu reduce 4,4′-bipyridine and reductively couple pyridine to afford the dimeric [{M III (NHAr iPr6 )2}2(µ-N2C10H8)] (2M, M = Y, La, Tm, Lu) and [{M III (NHAr iPr6 )2}2(µ-N2C10H10)] (3M, M = Y, La, Tm, Lu) respectively. These results contrast with electrochemical measurements, which place the RE(III/II) reduction potentials for all 1M complexes as insufficiently reducing for either heterocycle.

These results imply the reactions proceed through coordination-induced reduction. Synthesis of 2M complexes also results in the formation of 4,4′-bipyridine radical species, which are probed by NMR, EPR, and UV-Vis-NIR spectroscopies.</p><p dir="ltr"><br></p>