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Updated: Mar 14, 2026

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of PhosphorusI
Published on: November 22, 2016
A Stable Crystalline Triarylphosphine Oxide Radical Anion
Tobias A Schaub1, Eva M Zolnhofer2, Dominik P Halter2
1Chair of Organic Chemistry I, Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Henkestrasse 42, 91054, Erlangen, Germany.
Abstract:
Triarylphosphine oxides (Ar3 P=O) are being intensely studied as electron-accepting (n-type) materials. Despite the widespread application of these compounds as electron conductors, experimental data regarding the structural and electronic properties of their negatively charged states remain scarce owing to their propensity for follow-up chemistry. Herein, a carefully designed triarylphosphine oxide scaffold is disclosed that comprises sterically demanding spirofluorenyl moieties to shield the central phosphoryl (P=O) moiety. This compound undergoes chemical one-electron reduction to afford an exceptionally stable radical anion, which was isolated and characterized by X-ray crystallography for the very first time. The experimental data, corroborated by computational studies, shall allow for the construction of phosphine oxide materials with enhanced stability.
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