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Updated: Jun 23, 2026

Preparation of 6-aminocyclohepta-2,4-dien-1-one Derivatives via Tricarbonyl(tropone)iron
Published on: August 12, 2019
One- and two-electron coordinatively-induced reduction of N-heterocycles by divalent rare earth terphenyl anilide
Ross E MacKenzie1,2, Benjamin L L Réant1,2, Iain J Cameron1,2
1Centre for Radiochemistry Research, The University of Manchester Oxford Road Manchester M13 9PL UK conrad.goodwin@manchester.ac.uk.
Abstract:
Molecular rare-earth (RE) complexes in the divalent oxidation state have been used as potent one-electron reductants, yielding bonding motifs not accessible elsewhere in the periodic table. A deeper understanding of the chemical properties which dictate their reducing power is required to tame their reduction potentials and unlock new controlled reactivity. Here, we report the electrochemical characterisation of a series of divalent bis-(tethered)arene complexes, [Mii(NHAr iPr6)2] (1M, M = Y, La, Sm, Eu, Yb, Tm, Lu; NHAr iPr6 = {N(H)C6H3-2,6-(C6H2-2,4,6-iPr3)2}), and their reactivity towards the nitrogen heterocycles pyridine and 4,4'-bipyridine. Complexes 1Y, 1La, 1Tm, and 1Lu reduce 4,4'-bipyridine and reductively couple pyridine to afford the dimeric [{Miii(NHAr iPr6)2}2(µ-N2C10H8)] (2M, M = Y, La, Tm, Lu) and [{Miii(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.
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