A ¹⁹F n.m.r. study of group Va pentafluorides
Date
1976
Authors
Fowler, Brian Roy
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Abstract
The results of an ¹⁹F n.m.r. study of vanadium pentafluoride with the solvents perfluorocyclobutane, perfluoro(methylcyclohexane), sulphur hexafluoride, chlorine, bromine, hydrogen fluoride, bromine trifluoride, bromine pentafluoride, chlorine trifluoride, arsenic pentafluoride and antimony pentafluoride are presented and are discussed in terms of rapid fluorine exchange and in terms of the known behaviour of the similar pentafluorides NbF₅, TaF₅ and SbF₅. Evidence of donor character of VF₅ is given.
The ¹⁹F n.m.r. spectra of the reaction between phosphoryl trifluoride and vanadium pentafluoride are given and show an oxygen exchange reaction, with subsequent reaction between the products to give an adduct tentatively formulated as PF₅⋅OVF₃. The ¹⁹F n.m.r. spectra of the reaction of vanadium pentafluoride with trifluoracetic acid are presented and indicate an oxygen abstraction reaction.
The preparation and characterization of adducts of niobium pentafluoride and tantalum pentafluoride with the ligands ethylenediamine, ortho-phenanthroline, 2,2'bipyridyl, diethylenetriamine, and bis(acetylacetone)ethylenediimine and of niobium pentafluoride with 2-fluoropyridine, hexafluoroacetylacetone and trifluoroacetate are given and discussed. The ¹⁹F n.m.r. spectra of solutions of many of these adducts show the formation of the MF₆⁻ ion by a ligand redistribution reaction.