Syntheses, characterization, and crystal structures of the tetramethylammonium salts of the novel weakly coordinating anions [MeCO2{B(C6F5)3}]– and [MeCO2{B(C6F5)3}2]–

Abstract

The novel compounds [Me4N][MeCO2{B(C6F5)3}] and [Me4N][MeCO2{B(C6F5)3}2] are prepared and characterized spectroscopically and crystallographically. The compounds are salts of the unisolable acids MeCO2H·B(C6F5)3 and MeCO2H·2B(C6F5)3, respectively, which are sufficiently strong that they can protonate isobutene and initiate its carbocationic polymerization. The 1:1 adduct contains a conventional, monodentate acetate ion coordinated to the B(C6F5)3, while the 2:1 adduct contains a bridging acetate ligand.Key words: weakly coordinating anions, carbocationic polymerization, isobutene, polyisobutene.