Hexaphenyl-1,2-Diphosphonium Dication [Ph3P-PPh3]2+: Superacid, Superoxidant, or Super Reagent?

Dankert F, Muhm SP, Nandi C, Danés S, Mullassery S, Herbeck-Engel P, Morgenstern B, Weiß R, Salvador P, Munz D (2025)

Publication Type: Journal article

Publication year: 2025

Journal

Journal of the American Chemical Society American Chemical Society

DOI: 10.1021/jacs.5c01271

Abstract

The oxidation of triphenylphosphine by perfluorinated phenaziniumF aluminate in difluorobenzene affords hexaaryl-1,2-diphosphonium dialuminate 1. Dication 12+ is valence isoelectronic with elusive hexaphenylethane, where instead the formation of a mixture of the trityl radical and Gomberg’s dimer is favored. Quantum-chemical calculations in combination with Raman/IR spectroscopies rationalize the stability of the P-P bonded dimer in 12+ and suggest, akin to the halogens, facile homolytic as well as heterolytic scission. Thus, 12+ serves as a surrogate of both the triphenylphosphorandiylium dication (Ph3P2+) and the triphenylphosphine radical monocation (Ph3P·+). Treating 1 with dimethylaminopyridine (DMAP) or tBu3P replaces triphenylphosphine under heterolytic P-P bond scission. Qualifying as a superoxidant (E vs Fc/Fc+ = +1.44 V), 1 oxidizes trimethylphosphine. Based on halide abstraction experiments (-BF4 -PF6 -SbCl6 -SbF6) as well as the deoxygenation of triethylphosphine oxide, triflate anions as well as toluic acid, 1 also features Lewis superacidity. The controlled hydrolysis affords Hendrickson’s reagent, which itself finds broad use as a dehydration agent. Formally, homolytic P-P bond scission occurs with diphenyldisulfide (PhSSPh) and the triple bonds in benzo- and acetonitrile. The irradiation by light cleaves the P-P bond homolytically and generates transient triphenylphosphine radical cations, which engage in H-atom abstraction as well as CH phosphoranylation.

Authors with CRIS profile

Robert Weiß Naturwissenschaftliche Fakultät

Involved external institutions

Universität des Saarlandes (UdS) DE Germany (DE) Universitat de Girona ES Spain (ES) Leibniz-Institut für Neue Materialien gGmbH / Leibniz Institute for New Materials (INM) DE Germany (DE)

How to cite

APA:

Dankert, F., Muhm, S.P., Nandi, C., Danés, S., Mullassery, S., Herbeck-Engel, P.,... Munz, D. (2025). Hexaphenyl-1,2-Diphosphonium Dication [Ph3P-PPh3]2+: Superacid, Superoxidant, or Super Reagent? Journal of the American Chemical Society. https://doi.org/10.1021/jacs.5c01271

MLA:

Dankert, Fabian, et al. "Hexaphenyl-1,2-Diphosphonium Dication [Ph3P-PPh3]2+: Superacid, Superoxidant, or Super Reagent?" Journal of the American Chemical Society (2025).

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