Lewis Superacidic Divalent Bis(m‐terphenyl)element Cations [(2,6‐Mes2C6H3)2E]+of Group 13 Revisited and Extended (E=B, Al, Ga, In, Tl)

Abstract

AbstractIn a combined experimental and computational study, the molecular and electronic structures of the divalent bis(m‐terphenyl)element cations [(2,6‐Mes2C6H3)2E]+of group 13 (1, E=B;2, E=Al;3, E=Ga;4, E=In;5, E=Tl) were investigated. The preparation and characterization of2,3and5were previously reported by Wehmschulte's (Organometallics2004, 23, 1965–1967;J. Am. Chem. Soc.2003,125, 1470–1471) and our groups (Organometallics2009,28, 6893–6901). The indinium ion4was prepared and fully characterized for the first time. Attempts to prepare the borinium ion1by fluoride or hydride abstraction were unsuccessful. The electronic structures of1–5and the stabilization by the bulkym‐terphenyl substituents were analyzed using quantum chemical calculations and compared to the divalent bis(m‐terphenyl)pnictogenium ions [(2,6‐Mes2C6H3)2E]+of group 15 (6, E=P;7, E=As;8, E=Sb;9, E=Bi) previously investigated by our group (Angew. Chem. Int. Ed.2018,57, 10080–10084). The calculated fluoride ion affinities (FIA) of1–9are higher than that of SbF5, which classifies them as Lewis superacids.