Department of Chemistry, University of California, Davis, California 95616, United States.
J Am Chem Soc. 2011 Jan 19;133(2):180-3. doi: 10.1021/ja107380p. Epub 2010 Dec 14.
Reaction of a digermyne with cyclooctatetraene (cot) gave two isomeric products. A Ge(II) inverse sandwich is formed as the kinetic product, which was a result of complete Ge≡Ge bond cleavage and the formation of a π-bound cot ring. This isomerized in solution at room temperature over a period of 5 days to give the thermodynamic product, a tetracyclic diene-digermane, in which a single-bonded Ge-Ge moiety has inserted into a C═C bond of the cot carbocycle. Kinetic studies afforded an activation enthalpy (ΔH(‡)) and entropy (ΔS(‡)) of 14.9 kcal mol(-1) and -6.2 cal mol(-1) K(-1) respectively. Heating crystals of the thermodynamic product at ca. 120 °C cleanly regenerated the original inverse sandwich isomer.
二锗烷与环辛四烯（cot）反应生成两种非对映异构体产物。动力学产物为具有反夹心结构的 Ge(II)，这是由于完全的 Ge≡Ge 键断裂以及形成了一个 π 键合的 cot 环所致。该异构体在室温下的溶液中于 5 天内异构化，生成热力学产物，即四环二烯二锗烷，其中一个单键连接的 Ge-Ge 部分插入了 cot 碳环的 C═C 键中。动力学研究得到的活化焓（ΔH(‡)）和熵（ΔS(‡)）分别为 14.9 kcal mol(-1)和-6.2 cal mol(-1) K(-1)。在约 120°C 加热热力学产物的晶体，可干净地再生出原始的反夹心异构体。
