19F N.M.R. SPECTRA OF HEPTAVALENT FLUORIDES AND OXIDE PENTAFLUORIDES

Abstract

The 19F n.m.r. spectra of IF7, ReF7, IOF5, ReOF5, and OsOF5 have been recorded. IF7gives rise to a broad symmetric doublet with a splitting of 4 100 ± 300 c.p.s. interpreted as partially collapsed and unresolved 19F—127I coupling. ReF7 gives a single line of width 60 c.p.s. at low field. These spectra give no information about the molecular structure other than that there is a fast intramolecular process causing magnetic equivalence. IOF5 and ReOF5 both exhibit a quintet/doublet spectrum indicative of locked C4v symmetry. The multiplet splittings in IOF5 are not resolved in pure IOF5 or in IOF5/IF7 mixtures, but can be seen for IOF5 in solution in IF5. The doublet lies to higher field than the quintet in IOF5, but the reverse occurs in ReOF5. In the paramagnetic molecule OsOF5 only the resonance of the unique axial fluorine is observed, indicative of localization of the non-bonding d-electron in the equitorial plane of the molecule.