A Stable Aminyl Radical Metal Complex

Torsten Büttner (1) , Jens Geier (1) , Gilles Frison (1) , Jeffrey Harmer (1) , Carlos Calle (1) , Arthur Schweiger (1) , Hartmut Schönberg (1) , Hansjorg Grützmacher (1)

1 ETH Zürich - Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich]

Metal-stabilized phenoxyl radicals appear to be important intermediates in a variety of enzymatic oxidations. We report that transition metal coordination also supports an aminyl radical, resulting in a stable crystalline complex: [Rh(I)(trop2N°)(bipy)]+OTf- (where trop is 5-H-dibenzo[a,d]cycloheptene-5-yl, bipy is 2,2'-bipyridyl, OTf- is trifluorosulfonate). It is accessible under mild conditions by one-electron oxidation of the amide complex [Rh(I)(trop2N)(bipy)], at a potential of -0.55 volt versus ferrocene/ferrocenium. Both electron paramagnetic resonance spectroscopy and density functional theory support 57% localization of the unpaired spin at N. In reactions with H-atom donors, the Rh-coordinated aminyl behaves as a nucleophilic radical.

Mots clés: BOND-DISSOCIATION ENERGIES; EPR SPECTROSCOPY; CATALYSIS; LIGANDS; Density Functional Theory (DFT) calculations

Domaines: Chimie de coordination; Chimie théorique et/ou physique

Torsten Büttner, Jens Geier, Gilles Frison, Jeffrey Harmer, Carlos Calle, et al.. A Stable Aminyl Radical Metal Complex. Science, 2005, 307, pp.235-238. ⟨10.1126/science.1106070⟩. ⟨hal-00466464⟩