Interaction of N-trimethylsilylimidazole with electrophilic trimethylsilyl compounds. Part 2. Some exchange reactions involving bistrimethylsilylimidazolium salts

Abstract

The dynamic and equilibrium properties of bistrimethylsilimidazolium salts (1) have been investigated by n.m.r. spectroscopy. The salts (1) are highly susceptible to nucleophilic attack. The exchange reactions of (1) with electrophilic silanes (TMSX) have also been studied, in one example by the dynamic n.m.r. method of total line-shape analysis. The rate of the exchange reaction decrease (X = Cl > Br > CF₃SO₃ > I,CIO₄). The equilibrium constants for formation of (1) were found to decrease in the order Me₃SiClO₄ > Me₃SiOSO₂CF₃ > Me₃Sil > Me₃SiBr > Me₃SiCl. These results are shown to be consistent with silylation mechanisms involving silylated nucleophiles as intermediates.