Germacyclopentane, its 1-methyl, and 1,1-dimethyl derivatives together with some germacyclopentenes were prepared and their 13C and 73Ge NMR spectra were determined. Molecular mechanics calculations of germacyclopentanes indicate that the symmetric twist form is the most stable in contrast to cyclopentane where the envelop and twist forms have much the same energy. Though both 13C and 73Ge chemical shifts are less sensitive to the stereochemistry of the methyl group as compared with the corresponding germacyclohexanes, the spectroscopic results can be explained in terms of the structures as depicted by molecular mechanics calculations.
合取
环戊烷及其1-甲基和
1,1-二甲基衍
生物,以及一些合取
环戊烯被合成,并测定了它们的13C和73Ge NMR谱。合取
环戊烷的分子力学计算表明,在对比
环戊烷时,对称扭曲形式是最稳定的,而
环戊烷的包层和扭曲形式能量相差不大。尽管与对应的合取
环己烷相比,13C和73Ge
化学位移对甲基立体
化学的敏感性较低,但光谱结果可以通过分子力学计算所描绘的结构进行解释。