Amplifying Lewis Acidity by Oxidation: Leveraging the Redox-Activity of Bis(3,6-di-tert-butyl-catecholato)silane
Abstract
Bis(catecholato)silanes were showcased as strong Lewis acids, while their inherent redox activity remained unexplored in this context. In the present work, we study the oxidation of monomeric bis(3,6-di-tert-butyl-catecholato)silane (1), leading to the Lewis superacidic radicalic silylium ionradical 1•+ (FIA 784 kJ mol−1). Oxidation of 1 with [N(p-C6H4Br)3][B(C6F5)4] yielded [1][B(C6F5)4], displaying strong catalytic activity in the Friedel-Crafts-dimerization, hydrodeoxygenation and carbonyl-olefin-metathesis. It demonstrates how Lewis acidity can be amplified through oxidation without needing an add-on redox-active substituent. Instead, it synergizes the constraining effect of catecholates with their inherent redox non-innocence to unlock enhanced catalytic performance.