The so-called “Bergmann oxide” 4a and the related compounds 4b-i dissociate reversibly to the corresponding radicals 5 at elevated temperatures. Analysis of the ESR spectra reveals that in 5a-f the unpaired electron is delocalized over the entire molecule. On the other hand the strongly reduced spin density at the β-carbon atom in 5h-i as well as in 7 indicates a twisting about the N,N-bond in these
所谓的“伯格曼氧化物” 4a和相关的化合物4b-i在升高的温度下可逆地解离为相应的基团5。对ESR光谱的分析表明,在5a-f中,未配对的电子在整个分子上都离域化了。另一方面,在5h-i和7中,β-碳原子的自旋密度大大降低,这表明这些基团中的N,N-键扭曲,而m 5g,β-碳原子与Ar 1组被扭曲。自由基的自旋密度计算结果5与实验估算的自旋密度一致。在分别使用
亚硝基苯或亚硝基的自旋阱实验中,5a在β-碳原子上反应,表明该位置是反应性最高的位置。