Facile Access to Stable Silylium Ions Stabilized by N-Heterocyclic Imines

Abstract

Novel silylium ions with N-heterocyclic imines were successfully synthesized. The reaction of trimethylsilyl imidazolin-2-imine Me3SiNIPr (NIPr = bis(2,6-diisopropylphenyl)-imidazolin-2-imino) with B(C6F5)3 leads to dimeric imino-substituted silylium ions through a methyl group abstraction on the silicon atom. Meanwhile, the intermolecular imino-coordinated silylium ion is formed by using the less sterically crowded imine Me3SiNItBu (NItBu = bis(tert-butyl)-imidazolin-2-imino). Furthermore, the treatment of dimethylchlorosilane Me2(Cl)SiNIPr with AgOTf affords the contact ion pair Me2(OTf)SiNIPr by substitution of the chloride. A novel complex with the formula [Me2(DMAP)SiNIPr][OTf] was prepared by coordination with 4-dimethylamino-pyridine (DMAP). In the solid state, the DMAP adduct [Me2(DMAP)SiNIPr][OTf] contains a distinct [Me2(DMAP)SiNIPr]+ moiety.

Keywords

• silylium
• imine
• cation
• silicon
• borate