Tris(pentafluoroethyl)silanol Derivatives and the Lewis Amphoteric Tris(pentafluoroethyl)silanolate Anion, [Si(C2 F5 )3 O].

While alkyl-substituted siloxanes are widely known, virtually nothing is known about perfluoroalkyl siloxanes and their congener species, the silanols and silanolates. We recently reported on the tris(pentafluoroethyl)silanide ion, [Si(C2 F5 )3 ]- , which features Lewis amphoteric character deriving from the pentafluoroethyl substituents and their strong electron-withdrawing properties. Transferring this knowledge, we investigated the Lewis amphoteric behavior of the tris(pentafluoroethyl)silanolate, [Si(C2 F5 )3 O]- . In order to examine such Lewis amphoteric behavior, we first developed a strategy for the synthesis of the corresponding silanol Si(C2 F5 )3 OH, which readily condenses at room temperature to the hexakis(pentafluoroethyl)disiloxane, (C2 F5 )3 SiOSi(C2 F5 )3 . Deprotonation of Si(C2 F5 )3 OH employing a sterically demanding phosphazene base allows the characterization of the first example of a dimeric triorganosilanolate: the dianionic hexakis(pentafluoroethyl)disilanolate, [{Si(C2 F5 )3 O}2 ]2- , implies Lewis amphoteric character of the monomeric [Si(C2 F5 )3 O]- anion.