Reduction of Carbonyl Groups by Uranium(III) and Formation of a Stable Amide Radical Anion

• Published in: Chemistry : a European journal 2018-01, Vol.24 (4), p.826-837
• Main Authors: Mullane, Kimberly C., Cheisson, Thibault, Nakamaru‐Ogiso, Eiko, Manor, Brian C., Carroll, Patrick J., Schelter, Eric J.
• Format: Article
• Language: English
• Subjects: Benzaldehyde; Benzophenone; Carbonyl groups; Carbonyls; Chemistry; Crystallization; EPR spectroscopy; Methyl benzoate; Potassium; radicals; reactive intermediates; redox chemistry; uranium; Uranium compounds
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201703396

Methyl benzoate, N,N‐dimethylbenzamide, and benzophenone were reduced by UIII[N(SiMe3)2]3 resulting in uranium(IV) products. Reduction of benzophenone lead to UIV[OC⋅Ph2)][N(SiMe3)2]3, (1.1) which forms the dinuclear complex, [N(SiMe3)2]3UIV(OCPhPh‐CPh2O)UIV[N(SiMe3)2]3 (1.2), through coupling of the ketyl radical species upon crystallization. Reaction of N,N‐dimethylbenzamide with UIII[N(SiMe3)2]3 resulted in UIV[OC⋅(Ph)(NMe2)][N(SiMe3)2]3 (2), a uranium(IV) compound and the first example of a charge‐separated amide radical. In the case of methyl benzoate, the reduction resulted in UIV(OMe)[N(SiMe3)2]3 (3) and benzaldehyde as the reduced organic fragment. Compound 2 showed the ability to act as a uranium(III) synthon in its reactivity with trimethylsilyl azide, a reaction that yielded UV(=NSiMe3)[N(SiMe3)2]3. Additionally, 2 was reduced with potassium graphite resulting in [U(μ‐O)[O=C(NMe2)(Ph)][N(SiMe3)2]2]2 (4), a dinuclear uranium compound bridged by oxo ligands. Reduction of 2 in the presence of 15‐crown‐5 afforded isolation of the mono‐oxo compound, [(15‐crown‐5)2K][UO[N(SiMe3)2]3] (5). The results expand the reduction capabilities of UIII complexes and demonstrate a strategy for isolating novel metal‐stabilized radicals. U what? Methyl benzoate, N,N‐dimethylbenzamide, and benzophenone were reduced by UIII[N(SiMe3)2]3 resulting in uranium(IV) products. The results expand the reduction capabilities of UIII complexes and demonstrate a strategy for isolating novel metal‐stabilized radicals.