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Updated: Apr 19, 2026

Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of α,β-Unsaturated Compounds and Alkynes
Published on: December 16, 2019
An accurate molecular structure of phenyl, the simplest aryl radical
Oscar Martinez1, Kyle N Crabtree, Carl A Gottlieb
1Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (USA); Present address: Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, NM 87117 (USA).
Abstract:
The phenyl radical (C6H5(·)) is the prototypical σ-type aryl radical and one of the most common aromatic building blocks for larger ring molecules. Using a combination of rotational spectroscopy of singly substituted isotopic species and vibrational corrections calculated theoretically, an extremely accurate molecular structure has been determined. Relative to benzene, the phenyl radical has a substantially larger C-Cipso-C bond angle [125.8(3)° vs. 120°], and a shorter distance [2.713(3) Å vs. 2.783(2) Å] between the ipso and para carbon atoms.
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