Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States.
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States.
Inorg Chem. 2021 Dec 20;60(24):19165-19174. doi: 10.1021/acs.inorgchem.1c02981. Epub 2021 Dec 2.
Chalcogen-containing carboranes have been known for several decades and possess stable exopolyhedral B(9)-Se and B(9)-Te σ bonds despite the electron-donating ability of the B(9) vertex. While these molecules are known, little has been done to thoroughly evaluate their electrophilic and nucleophilic behavior. Herein, we report an assessment of the electrophilic reactivity of -carboranylselenyl(II), -tellurenyl(II), and -tellurenyl(IV) chlorides and establish their reactivity pattern with Grignard reagents, alkenes, alkynes, enolates, and electron-rich arenes. These electrophilic reactions afford unique electron-rich B-Y-C (Y = Se, Te) bonding motifs not commonly found before. Furthermore, we show that -carboranylselenolate, and even -carboranyltellurolate, can be competent nucleophiles and participate in nucleophilic aromatic substitution reactions. Arene substitution chemistry is shown to be further extended to electron-rich species via palladium-mediated cross-coupling chemistry.
含硫属元素的碳硼烷已经存在了几十年，尽管 B(9)顶点具有供电子能力，但它们仍具有稳定的多面体 B(9)-Se 和 B(9)-Te σ 键。虽然这些分子已经为人所知，但对它们的亲电和亲核行为进行彻底评估的工作却很少。在此，我们报告了对 -carboranylselenyl(II)、-tellurenyl(II)和 -tellurenyl(IV) 氯化物的亲电反应性的评估，并确定了它们与格氏试剂、烯烃、炔烃、烯醇盐和富电子芳环的反应模式。这些亲电反应提供了以前不常见的独特的富电子 B-Y-C（Y = Se、Te）键合模式。此外，我们还表明 -carboranylselenolate，甚至 -carboranyltellurolate，都可以作为亲核试剂，并参与亲核芳香取代反应。芳环取代化学进一步通过钯介导的交叉偶联化学扩展到富电子物种。
