Asymmetric dimerization of aniline–ruthenium–dioxolene complex driven by stepwise PCET

After double deprotonation, 2,6-diaryl-p-benzoquinonodiimidazoles (aryl=4-tolyl (I) or 2-pyridyl (II)) were shown to bridge two [Ru(bpy) ] (bpy=2,2'-bipyridine) complex fragments through the imidazolate N and p-quinone O (I→1 ) or through the imidazolate N and pyridyl N donor atoms (II→2 ). Characterization by crystal structure analysis, H/ C NMR spectroscopy, cyclic and differential pulse voltammetry, and spectroelectrochemistry (UV/Vis/NIR, IR, EPR) in combination with TD-DFT calculations revealed surprisingly different electronic structures for redox systems 1 and 2 . Whereas 1 is reduced to a radical complex with considerable semiquinone character, the reduction of 2 with its exclusive N coordination exhibits little spin on the now redox-innocent quinone moiety, compared with the electron uptake by the pyridyl-imidazolate chelating site. The first of two close-lying oxidation processes occurs at the bridging heteroquinone ligand, whereas the second oxidation is partly (1 ) or predominantly (2 ) centered on the metal atoms.

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Reactivity of Rhodium(II) amido/Rhodium(I) aminyl complexes

Zhang

Zhu

Herbert

et al. 2018

Inorganica Chimica Acta

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Reaction of the Rh(II) dimer [LRh] 2 (μ-Br) 2 (L = ([2,6-Me 2 C 6 H 3 NCMe] 2 CH) with the bulky amide LiNH (2,6-i Pr 2 C 6 H 3) leads to a monomeric Rh(II) amide with a T-shape N 3 Rh arrangement and a pronounced agostic interaction. Reaction with the less bulky LiNH(2,6-Me 2 C 6 H 3) results in benzylic C-H activation to a binuclear complex with a unique aza-xylylene bridging mode. With LiNHC 6 H 5 we observe initial formation of [LRh] 2 (μ-NHPh) 2 followed by N,C2′ coupling of two anilines. These reactions can be explained based on aminyl radical character of the Rh(II) amides (supported by EPR evidence) and/or involvement of nitrene intermediates.

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Asymmetric dimerization of aniline–ruthenium–dioxolene complex driven by stepwise PCET

Cited by 3 publications

References 42 publications

Complexes of Stable N ‐aryl Radicals and Their Catalytic Applications

Complexes of Stable N ‐aryl Radicals and Their Catalytic Applications

Diruthenium Complexes of p‐Benzoquinone–Imidazole Hybrid Ligands: Innocent or Noninnocent Behavior of the Quinone Moiety

Reactivity of Rhodium(II) amido/Rhodium(I) aminyl complexes

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