Isolation of crystalline carbene-stabilized P2-radical cations and P2-dications

The discovery in 1900 by Gomberg that the trityl radical (Ph 3 C · ) exists at room temperature is often considered to be the beginning of radical chemistry. Since then, persistent and even room-temperature stable radicals based on second-row and heavier elements have been synthesized. However, few...

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Published inNature chemistry Vol. 2; no. 5; pp. 369 - 373
Main Authors Back, Olivier, Donnadieu, Bruno, Parameswaran, Pattiyil, Frenking, Gernot, Bertrand, Guy
Format Journal Article
LanguageEnglish
Published London Nature Publishing Group UK 01.05.2010
Nature Publishing Group
Subjects
639/638/263
Analytical Chemistry
Biochemistry
Cations
Chemistry
Chemistry and Materials Science
Chemistry/Food Science
Electrons
Inorganic Chemistry
NMR
Nuclear magnetic resonance
Organic Chemistry
Oxidation
Phosphorus
Physical Chemistry
United States > US
California
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Summary:The discovery in 1900 by Gomberg that the trityl radical (Ph 3 C · ) exists at room temperature is often considered to be the beginning of radical chemistry. Since then, persistent and even room-temperature stable radicals based on second-row and heavier elements have been synthesized. However, few of them have been characterized crystallographically, because they are either too reactive or dimerize in the solid state. Here, we show that a P 2 fragment, capped with two bulky, strongly electron-releasing singlet carbenes (dicoordinate carbon compounds with only six valence electrons), can undergo one-electron oxidation, giving rise to room-temperature stable radical cations. Moreover, when N -heterocyclic carbenes are used, two-electron oxidation can also be performed, producing the corresponding stable dicationic diphosphene, which has to be regarded as a P 2 2+ fragment coordinated by two carbenes. These results reveal a new application of stable singlet carbenes, the stabilization of paramagnetic species and electron-poor fragments. N -heterocyclic carbenes have been shown to be versatile ligands for metal catalysts and even catalysts in their own right. Here, bulky N -heterocyclic carbenes are shown to stabilize paramagnetic and electron-poor species sufficiently for their crystallographic characterization.
ISSN:1755-4330
1755-4349
DOI:10.1038/nchem.617