Cerium(IV) fluoride complexes in solutions

Abstract

The first complexes of Ce(IV)fluoride in solution have been observed and studied by 19F{1H}, 1H NMR and IR spectroscopy in saturated solutions of CeF4*H2O in Me2SO diluted by CH3CN or CH2Cl2. On the base of analysis of the temperature dependence of the 19F{1H} NMR spectra and the assumption that the usual for the solid Ce(IV) fluorocomplexes square antiprism coordination polyhedron is retained in the solution, the conclusion has been made that dynamic equilibrium between the molecular adduct [CeF4(Me2SO)4] and ionic forms [CeF3(Me2SO)5]+ and [CeF5(Me2SO)3]− exists in solution, including geometric isomers. The statistical probability of formation of [CeF4(Me2SO)4] and [CeF5(Me2SO)3]− stereoisomers has been calculated. Quantum chemical calculations of the structures of some visually distinguishable isomers of [CeFn(Me2SO)8-n]4-n (n=3–5) and [CeF4(Me2SO)3(H2O)] showed their thermodynamic stability. The experimental IR spectrum of the solution is in a good agreement with calculated spectra of [CeFn(Me2SO)8-n]4-n and [CeF4(Me2SO)3(H2O)] stable complexes.