Identification by Raman spectroscopy of various weak oxygen-bridged donor–acceptor adducts of arsenic and antimony pentafluorides; a reversal of the usual Lewis acidities of these pentafluorides towards sulphuryl fluoride

Abstract

The compounds POF₃, SO₂, SOF₂, and COF₂ form 1 : 1 oxygen-bridged adducts with AsF₅ and SbF₅ as shown from their Raman spectra obtained at various temperatures. The base strength of the donors appears to decrease in the given order. Sulphuryl fluoride behaves as a still weaker base; however, Raman spectra show the formation of an oxygen-bridged 1 : 1 adduct with AsF₅, but not SbF₅, a reversal of the usual Lewis acidities.