Radical Formation by Direct Single Electron Transfer between Nitrobenzene and Anionic Organo Bases

Area of Science:

• Organic Chemistry
• Physical Chemistry
• Spectroscopy

Background:

• Organic radicals possess unique magnetic and reactivity properties.
• Their application is limited by the challenging chemistry and strict structural requirements for their preparation.
• Facile radical formation under mild conditions is key to unlocking their potential.

Purpose of the Study:

• To develop a general protocol for facile radical formation using readily available starting materials.
• To explore nitroarenes as versatile radical precursors.
• To investigate the potential of organic bases and nitrobenzene in radical generation.

Main Methods:

• Electron paramagnetic resonance (EPR) spectroscopy.
• Ab initio quantum chemical calculations.
• Single electron transfer reactions involving anionic organic bases and nitrobenzene.

Main Results:

• An unprecedented single electron transfer from anionic organic bases (B^-X⁺) to nitrobenzene was observed.
• Stable nitrobenzenide radical ion-pairs [1^•-]-[X⁺] and transient oxidized radical bases (B^•) were formed.
• Nitroarenes were established as effective radical precursors.

Conclusions:

• A broadly applicable protocol for generating heteroatom-centered radicals under mild conditions was established.
• The study provides a method using inexpensive and readily available starting materials.
• The [1]-[B^-X⁺] couple presents a novel platform for frustrated radical pair research.