EPR studies of some vanadium oxyfluoro anionic complexes

Abstract

The EPR of Vanadium (IV) in natural abundance of KVO₂F₂0.5H₂O[A], K₂VO₂F₃0.5H₂O[B], K₃VO₂F₄[C], and K₃VOF₆[D], prepared by a solid state route, was studied at different temperatures in the range 77-573K. The spectra of compounds A and B are nearly temperature independent and are characteristic of a rigid anion. Only in compound B, the ¹⁹F super hyperfine structure can be seen well resolved on one of the perpendicular components even at room temperature. The EPR spectra of compounds C and D are characterised by the presence of discrete anionic species, and, depending on the temperature, some of the anions are in rigid state while the others are in re-orienting state. EPR and DSC studies indicate the occurrence of a first order phase transition in these two compounds.

Key Words:

• Electron paramagnetic resonance
• structural phase transition
• superhyperfine structure
• vanadium oxyfluoro anions