Abstract
The known boranes (R(Me(3) Si)N)(2) BF (R=Me(3) Si 1, tBu 2, C(6) F(5) 3, o-tol 4, Mes 5, Dipp 6) and borinium salts (R(Me(3) Si)N)(2) B][B(C(6) F(5) )(4) ] (R=Me(3) Si 7, tBu 8) are prepared and fully characterized. Compound 7 is shown to react with phosphines to generate [R(3) PSiMe(3) ](+) and [R(3) PH](+) (R=Me, tBu). Efforts to generate related borinium cations via fluoride abstraction from (R(Me(3) Si)N)(2) BF (R=C(6) F(5) 3, o-tol 4, Mes 5) gave complex mixtures suggesting multiple reaction pathways. However for R=Dipp 6, the species [(μ-F)(SiMe(2) N(Dipp))(2) BMe][B(C(6) F(5) )(4) ] was isolated as the major product, indicating methyl abstraction from silicon and F/Me exchange on boron. These observations together with state-of-the-art DFT mechanistic studies reveal that the trimethylsilyl-substituents do not behave as ancillary subsitutents but rather act as sources of proton, SiMe(3) and methyl groups.