Rhodium-Mediated C–C Bond Activation of 2-(2′,6′-Dialkylarylazo)-4-methylphenols. Elimination and Migration of Alkyl Groups

Baksi, Suparna and Acharyya, Rama and Basuli, Falguni and Peng, Shie M and Lee, Gene H and Nethaji, Munirathinam and Bhattacharya, Samaresh (2007) Rhodium-Mediated C–C Bond Activation of 2-(2′,6′-Dialkylarylazo)-4-methylphenols. Elimination and Migration of Alkyl Groups. In: Organometallics, 26 (26). pp. 6596-6603.

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Abstract

Upon reaction of 2-(2′,6′-dimethylphenylazo)-4-methylphenol with $[Rh(PPh_3)_3Cl]$, the azo ligand undergoes an interesting rhodium-assisted C–C bond activation at one ortho position of the 2′,6′-dimethylphenyl fragment, leading to the elimination of the methyl group from that ortho position. A similar elimination of an ethyl group takes place when 2-(2′,6′-diethylphenylazo)-4-methylphenol is allowed to react with $[Rh(PPh_3)_3Cl]$. However, when 2-(2′,6′-diisopopylphenylazo)-4-methylphenol reacts with $[Rh(PPh_3)_3Cl]$, an interesting migration of an isopropyl group from its original location (say the 2′ position) to the corresponding third position (say the 4′ position) takes place. In all the three complexes the modified azo ligands bind to rhodium as dianionic C,N,O-donors, and two triphenylphosphines and a chloride are also coordinated to the metal center. Structures of all three complexes have been determined by X-ray crystallography. These complexes show characteristic 1H NMR signals and intense MLCT transitions in the visible region. Cyclic voltammetry on these complexes shows a Rh(III)–Rh(IV) oxidation on the positive side of SCE and a reduction of the coordinated azo ligand on the negative side.

Item Type:	Journal Article
Publication:	Organometallics
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	05 Jun 2008
Last Modified:	24 Feb 2012 07:35
URI:	http://eprints.iisc.ac.in/id/eprint/14193

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