have been prepared from the appropriate triarylmetal chloride, MAr3Cl, and an electron-rich olefin [R]2 (R = Me or Et) under UV irradiation in toluene at low temperature. The triarylgermyl radicals are persistent (t > 24 h, 20°C) whilst the analogous tin and silicon radicals are only stable under constant irradiation at temperatures below −20°C; the ESR spectra of the germanium radicals and of .Si(2
以三芳基
金属为中心的自由基。MAr 3(M = Si,Ge或Sn; Ar = 2,6-Me 2 C 6 H 3或2,4,6-Me 3 C 6 H 2)已由适当的三芳基
金属
氯化物MAr 3 Cl制备,以及在低温下在
甲苯中紫外线照射下的富电子烯烃[ R] 2(R = Me或Et)。三芳基
锗烷基自由基具有持久性(t > 24 h,20°C),而类似的
锡和
硅自由基仅在低于-20°C的恒定辐射下稳定。
锗自由基和
锗的ESR谱。Si(2,4,6-Me 3C 6 H 2)3(它是第一个被光谱鉴定的三芳基甲
硅烷基基团)显示出所有质子偶合的等价等效物,这是由于芳族环扭曲成围绕
金属的“螺旋桨”排列所致。还报道了这些自由基的前体的合成和表征。