ELECTRON SPIN RESONANCE AND CHEMICAL STUDIES ON THE 6-(TRIMETHYLSILYL)CYCLOHEXADIENYL AND RELATED RADICALS.

Article abstract of DOI:10.1021/ja00359a013

Various 3,6-disubstituted cyclohexadienyl radicals were generated and investigated by ESR at low temperature. Analysis of the ESR parameters indicated that the significant out-of-plane deformation of the carbon framework of 6-Me//3Si- and 6-Me//3Ge-substituted cyclohexadienyl radicals occurred to gain stabilization due to the effective hyperconjugation between the substituted methylene pseudo- pi orbital and the pi SOMO, while the 6-unsubstituted and 6-t-Bu cyclohexadienyl radicals were essentially planar. Investigation of the fate of the 3,6-bis(trimethylsilyl)cyclohexadienyl radical showed strong evidence for the temperature-dependent reversibility of the silyl radical addition to aromatics. The spontaneous elimination of the trimethylsilyl radical was proved by spin-trapping experiments.