B(C₆F₅)₃ catalysis accelerates the hydrosilane chlorination by Ph₃CCl

Abstract

A chlorination of tertiary (5 examples), secondary (3 examples) and primary (PhSiH3) hydrosilanes by Ph3CCl with a catalytic amount of B(C6F5)3 is presented. The reaction was substantially faster than its non‐catalyzed version. The chlorination of secondary hydrosilanes and PhSiH3 proceeded in a stepwise manner, which allowed selective isolation of chlorohydrosilanes. The mechanism of catalytic hydrosilane chlorination seems to be distinct to mainstream B(C6F5)3 catalyzed reactions involving hydrosilanes (i.e. activation of Si‐H bond by the R3Si‐‐H‐‐B (C6F5)3 adduct formation). Contrary, the present process is based on an instant formation of [Ph3C]+[ClB(C6F5)3]− from B(C6F5)3 and Ph3CCl, followed by a hydride transfer from particular hydrosilane to tritylium cation with a concomitant generation of unstable silylium cation compensated by borate anion [ClB(C6F5)3]−. Subsequent decomposition of this ionic species leads to the corresponding chlorosilane and recuperation of B(C6F5)3.

Challenges in the Electrochemical Synthesis of Si2Cl6 Starting from Tetrachlorosilane and Trichlorosilane

“…Applying this concept to the activation of HSiCl 3 , CV measurements indicate that the activation of electron-poor Hsilanes is hindered by the Lewis acidity of HSiCl 3 itself as has been mentioned in literature. [38] B(C 6 F 5 ) 3 is oxidized with a peak potential at 2.26 V vs. FcH/FcH + at GC, an identical trend is obtained by HSiCl 3 with 5 mol % of B(C 6 F 5 ) 3 (Figure 4). Neither the previously mentioned oxidation wave at 0.88 V vs. FcH/ FcH + nor the increase of oxidation current at GC electrode is observed.…”