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Updated: Jul 5, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
The isolable cation radical of disilene: synthesis, characterization, and a reversible one-electron redox system
Shigeyoshi Inoue1, Masaaki Ichinohe, Akira Sekiguchi
1Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
Abstract:
The highly twisted tetrakis(di-tert-butylmethylsilyl)disilene 1 was treated with Ph3C+.BAr4- (BAr4-: TPFPB = tetrakis(pentafluorophenyl)borate) in toluene, producing disilene cation radical 3 upon one-electron oxidation. Cation radical 3 was isolated in the form of its borate salt as extremely air- and moisture-sensitive red-brown crystals. The molecular structure of 3 was established by X-ray crystallography, which showed a highly twisted structure (twisting angle of 64.9 degrees) along the central Si-Si bond with a bond length of 2.307(2) A, which is 2.1% elongated relative to that of 1. The cation radical is stabilized by sigma-pi hyperconjugation by the four tBu2MeSi groups attached to the two central sp2-Si atoms. An electron paramagnetic resonance (EPR) study of the hyperfine coupling constants (hfcc) of the 29Si nuclei indicates delocalization of the spin over the central two Si atoms. A reversible one-electron redox system between disilene, cation radical, and anion radical is also reported.
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