Publication Date:
2019
Description:
〈p〉Hydrogen-substituted silylium ions are long-sought reactive species. We report a protolysis strategy that chemoselectively cleaves either an Si–C(sp〈sup〉2〈/sup〉) or an Si–H bond using a carborane acid to access the full series of [CHB〈sub〉11〈/sub〉H〈sub〉5〈/sub〉Br〈sub〉6〈/sub〉]〈sup〉–〈/sup〉-stabilized R〈sub〉2〈/sub〉SiH〈sup〉+〈/sup〉, RSiH〈sub〉2〈/sub〉〈sup〉+〈/sup〉, and SiH〈sub〉3〈/sub〉〈sup〉+〈/sup〉 cations, where bulky 〈i〉tert〈/i〉-butyl groups at the silicon atom (R = 〈i〉t〈/i〉Bu) were crucial to avoid substituent redistribution. The crystallographically characterized molecular structures of [CHB〈sub〉11〈/sub〉H〈sub〉5〈/sub〉Br〈sub〉6〈/sub〉]〈sup〉–〈/sup〉-stabilized 〈i〉t〈/i〉Bu〈sub〉2〈/sub〉HSi〈sup〉+〈/sup〉 and 〈i〉t〈/i〉BuH〈sub〉2〈/sub〉Si〈sup〉+〈/sup〉 feature pyramidalization at the silicon atom, in accordance with that of 〈i〉t〈/i〉Bu〈sub〉3〈/sub〉Si〈sup〉+〈/sup〉[CHB〈sub〉11〈/sub〉H〈sub〉5〈/sub〉Br〈sub〉6〈/sub〉]〈sup〉–〈/sup〉. Conversely, the silicon atom in the H〈sub〉3〈/sub〉Si〈sup〉+〈/sup〉 cation adopts a trigonal-planar structure and is stabilized by two counteranions. This solid-state structure resembles that of the corresponding Brønsted acid.〈/p〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
Permalink