| The novel compounds [Me4N][MeCO2{lcub}B(C6F 5)3{rcub}] and [Me4N][MeCO2{lcub}B(C 6F5)3{rcub}2] are prepared and characterized spectroscopically and crystallographically. The compounds are salts respectively of the unisolable acids MeCO2H·B(C6F5) 3 and MeCO2H·2B(C6F5)3 , which are sufficiently strong that they can protonate isobutene and initiate its carbocationic polymerization. Through X-ray crystallography and IR spectrometry, it is shown that 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.; Since the nature of the conjugate acids of these salts has to this point been inferred only from their solution chemistry, the identification and characterization of the species in solution was carried out. A spectroscopic investigation (IR, 1H, 11B, 13C and 19F NMR spectrometry) of the adducts formed in CH2Cl 2 solution on combining B(C6F5)3 with a variety of carboxylic acids has been successfully performed, and results with propanoic acid demonstrate that novel, stable adducts such as C 2H5CO2H·B(C6F5) 3 are indeed formed.; In order to study the synthesis of increasingly high molecular weight polyisobutene at relatively high temperatures (≤ -30°C), metal-free initiating systems based on the reaction of B(C6F5) 3 with several carboxylic acids, CH3(CH2) nCO2H (where n = 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20) were assessed. The chain length effects of this strong acid, carbocationic polymerization initiating system have been considered. |
