Fluorine exchange between four-, five-, and six-coordinate silicon compounds

Abstract

Intermolecular fluorine exchange in the systems SiF₄–SiF₅⁻, MeSiF₃–MeSiF₄⁻, PhSiF₃–PhSiF₄⁻, SiF₅⁻–SiF₆²⁻, SiF₄–SiF₆²⁻, and MeSiF₃–SiF₆²⁻ has been studied by fluorine and proton nmr spectroscopy. Exchange is postulated to involve fluorine-bridged intermediates; alternative pathways of exchange, such as fluoride dissociation or impurity (HF and H₂O) catalyzed exchange, have been eliminated. Addition of NH₃ to SiF₅⁻–SiF₆²⁻ slows down exchange whereas addition of Et₂NH to MeSiF₃ promotes exchange.