Vanadium(V) fluoride complexes in organic solvents. Avanadium-51 and fluorine-19 nuclear magnetic resonance study

Abstract

The complexes [VOCI_(4–n)F_n]^–(n= 1–4), [VO(CF₃CO₂)_(4–n)F_n]^–(n= 1–3), [VOF₃(NO₃)]^–[VOF₃(MeSO₃)]^–, [VO₂CIF]^–, [VOF₃(bipy)](bipy = 2,2′-bipyridine), [VOF₃(phen)](phen = 1, 1 0-phenanthroline), VOCI₂F·_nMeCN, and VOCIF₂·nMeCN have been characterised in organic solvents by ⁵¹V and ¹⁹F n.m.r. spectroscopy. Most of the fluoro complexes display vanadium–fluorine coupling, the magnitude of which depends upon the degree of covalency of the vanadium–fluorine bond. Two isomers of [VOCI₂F₂]^– and [VO(CF₃CO₂)₂F₂]^– were observed indicating a square-pyramidal geometry for these anions. [VOF₃(NO₃)]^–, [VOF₃(bipy)], and [VOF₃(phen)] are probably pseudo-octahedral. All the [VOF₃X]^–(X = Cl, CF₃CO₂, NO₃, or MeSO₃) anions show fluxional behaviour.