Hull Michael W, Sevov Slavi C
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
J Am Chem Soc. 2009 Jul 1;131(25):9026-37. doi: 10.1021/ja9025962.
Presented are the results of a systematic investigation of the reactions of nine-atom deltahedral clusters of germanium (Zintl ions, Ge(9)(n-)) with alkynes and alkyl halides that result in alkenylation and alkylation of the clusters, respectively. The reaction pathways have been probed in depth using various, appropriately substituted alkynes and organic halides, including some typical mechanistic probes and radical clocks. The regioselectivity and stereoselectivity of the reaction with alkynes was examined by systematically varying the steric and electronic nature of the substituents. The studies showed that the Zintl clusters act as strong, anionic nucleophiles toward the alkynes and primary and secondary alkyl halides but, most likely, as electron donors in reactions with tertiary alkyl halides and halogenated olefins. The pentenyl and methylcyclopropyl functionalized clusters, Ge(9)(C(5)H(9)) and Ge(9)(CH(2)CH(CH(2))(2)), respectively, were crystallographically characterized in compounds with K-crypt countercations. All compounds were also analyzed by NMR and electrospray mass spectrometry.
本文展示了对锗的九原子二十面体簇（Zintl离子，Ge(9)(n-)）与炔烃和卤代烃反应的系统研究结果，这些反应分别导致簇的烯基化和烷基化。使用各种适当取代的炔烃和有机卤化物，包括一些典型的机理探针和自由基时钟，对反应途径进行了深入探究。通过系统地改变取代基的空间和电子性质，研究了与炔烃反应的区域选择性和立体选择性。研究表明，Zintl簇对炔烃以及伯卤代烃和仲卤代烃表现为强阴离子亲核试剂，但在与叔卤代烃和卤代烯烃的反应中很可能作为电子供体。分别以K-crypt抗衡阳离子对戊烯基和甲基环丙基官能化的簇Ge(9)(C(5)H(9))和Ge(9)(CH(2)CH(CH(2))(2))进行了晶体学表征。所有化合物还通过核磁共振和电喷雾质谱进行了分析。
