An Estimate of the Reduction Potential of B(C₆F₅)₃ from Electrochemical Measurements on Related Mesityl Boranes

Abstract

MesB(C6F5)2 (1) has been prepared from MesMgBr and FB(C6F5)2·OEt2, while Mes2B(C6F5) (2) is readily available from CuC6F5 and Mes2BBr. The reduction potential E° of 1 vs Cp2Fe0/+ in THF is −1.72 V, while that of 2 is −2.10 V, and that of Mes3B (3) is −2.73 V. 11B and 1H NMR show that neither 1 nor 2 binds THF significantly. These results have been used to estimate the reduction potential of B(C6F5)3 in THF as −1.17 V vs Cp2Fe0/+ or as −0.64 V vs SCE.