Synthesis, Structure, and Electrochemical Properties of a Family of 2-(Arylazo)phenolate Complexes of Ruthenium with Unusual C-C Coupling and N=N Cleavage

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• 作者：Sarmistha Halder ; Rama Acharyya ; Shie-Ming Peng ; Gene-Hsiang Lee ; Michael G. B. Drew ; Samaresh Bhattacharya
• 刊名：Inorganic Chemistry
• 出版年：2006
• 出版时间：November 27, 2006
• 年：2006
• 卷：45
• 期：24
• 页码：9654 - 9663
• 全文大小：256K
• 年卷期：v.45,no.24(November 27, 2006)
• ISSN：1520-510X

文摘

Reaction of 2-(4'-R-phenylazo)-4-methylphenols (R = OCH₃, CH₃, H, Cl, and NO₂) with [Ru(dmso)₄Cl₂] affords afamily of five ruthenium(III) complexes, containing a 2-(arylazo)phenolate ligand forming a six-membered chelatering and a tetradentate ligand formed from two 2-(arylazo)phenols via an unusual C-C coupling linking the twoortho carbons of the phenyl rings in the arylazo fragment. A similar reaction with 2-(2'-methylphenylazo)-4-methylphenolwith [Ru(dmso)₄Cl₂] has afforded a similar complex, in which one 2-(2'-methylphenylazo)-4-methylphenolate ligandis coordinated forming a six-membered chelate ring, and the other two ligands have undergone the C-C couplingreaction, and the coupled species is coordinated as a tetradentate ligand forming a five-membered N,O-chelatering, a nine-membered N,N-chelate ring, and another five-membered chelate ring. Reaction of 2-(2',6'-dimethylphenylazo)-4-methylphenol with [Ru(dmso)₄Cl₂] has afforded a complex in which two 2-(2',6'-dimethylphenylazo)-4-methylphenols are coordinated as bidentate N,O-donors forming five- and six-membered chelate rings,while the third one has undergone cleavage across the N=N bond, and the phenolate fragment, thus generated,remains coordinated to the metal center in the iminosemiquinonate form. Structures of four selected complexeshave been determined by X-ray crystallography. The first six complexes are one-electron paramagnetic and showrhombic ESR spectra. The last complex is diamagnetic and shows characteristic ¹H NMR signals. All the complexesshow intense charge-transfer transitions in the visible region and a Ru(III)-Ru(IV) oxidation on the positive side ofSCE and a Ru(III)-Ru(II) reduction on the negative side.