A Highly Stable Cyclic (Amino)(Aryl)Nitrenium Radical Dication Exhibiting Temperature-Dependent Radical Bistability Maruti Suryavansi,a Manas Khatua,b,d Bappaditya Goswami,c Apurba Kumar Pal,a Subhas Samanta,*d and K. Geetharani*
Year: 2026
Type: preprint
Abstract: Development of air- and thermally stable organic radicals remains challenging due to the highly transient nature of the free radicals. Herein, we present a strategy for isolating a highly stable N-heterocyclic carbenes (NHCs) stabilized cyclic (amino)(aryl)nitrenium (CAArN) radical. This is the first example of a CAArN radical isolated in the solid state, and its identity has been confirmed by single-crystal X-ray diffraction and various spectroscopic studies. These CAArN radical exhibits remarkable stability towards air, water, strong acidic/alkaline conditions, aqueous buffers, and high temperature (~412 °C). The radical residing on two distinct redoxactive motifs exhibits unique temperature-dependent bistability in solution, as evidenced by VT-EPR and VT-UV-vis spectral studies. Polar solvents have played a crucial role in stabilizing the imidazolium motif, thereby facilitating the radical bistability. Further, by employing KC8, selective reduction of the NHC-moiety bonded to the CAArN radical was achieved to yield Thiele’s type hybrid diradicaloid.
Source: ChemRxiv
Author: Geetharani K
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7221810335