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Interaction of 2-(arylazo)phenols with rhodium. Usual coordination vs. C-H and C-C activation |
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| Authors: | Suparna Baksi Swati Dutta Michael G.B. Drew |
| Affiliation: | a Department of Chemistry, Inorganic Chemistry Section, Jadavpur University, Kolkata 700 032, India b School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK c Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, UK |
| Abstract: | Reaction of 2-(2′-hydroxyphenylazo)phenol with [Rh(PPh3)3Cl] in refluxing benzene in presence of triethylamine afforded a red complex in which the ligand is coordinated to rhodium as a tridentate O,N,O-donor. However, similar reaction of [Rh(PPh3)3Cl] with 2-(2′-carboxyphenylazo)-4-methylphenol yielded two complexes, viz. a blue one and a green one. In both the complexes the ligand is coordinated as C,N,O-donor. However, in the blue complex orthometallation takes place from the ortho-carbon atom, which bears -COOH group via decarboxylation and in green one orthometallation occurs from the other ortho-carbon. Structures of all the three complexes were determined by X-ray crystallography. In all the three complexes rhodium is sharing the equatorial plane with the tridentate ligand and a chloride, and the two triphenylphosphines are axially disposed. All of the complexes show 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 azophenolate ligand on the negative side. |
| Keywords: | 2-(Arylazo)phenols Rhodium Usual coordination C-H and C-C activation |
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