Catalytic N−N Coupling of Aryl Azides To Yield Azoarenes via Trigonal Bipyramid Iron−Nitrene Intermediates

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• 作者：Neal P. Mankad ; Peter Mller ; Jonas C. Peters
• 刊名：Journal of the American Chemical Society
• 出版年：2010
• 出版时间：March 31, 2010
• 年：2010
• 卷：132
• 期：12
• 页码：4083-4085
• 全文大小：190K
• 年卷期：v.132,no.12(March 31, 2010)
• ISSN：1520-5126

文摘

The reactivity of the trigonal bipyramidal iron(I) complex [SiP^iPr₃]Fe(N₂) ([SiP^iPr₃] = (2-iPr₂PC₆H₄)₃Si⁻) toward organoazides has been examined. 1-Adamantylazide was found to coordinate the iron center to form stable [SiP^iPr₃]Fe(η¹-N₃Ad). Aryl azides instead afforded unstable [SiP^iPr₃]Fe(N₃Ar) species that decayed gradually to regenerate [SiP^iPr₃]Fe(N₂) with release of azoarenes (ArN═NAr). The conversion of aryl azides to azoarenes can thus be achieved catalytically. Competitive trapping experiments strongly suggest the intermediacy of reactive nitrene complexes of the type [SiP^iPr₃]Fe(NAr) that couple bimolecularly in the N−N bond forming step. Evidence for one such intermediate was provided by electron paramagnetic resonance spectroscopy via photolysis of [SiP^iPr₃]Fe(N₃Ar) in a frozen glass. The electronic structures of these putative nitrene intermediates have been examined by DFT methods.