Synthesis, structures and characterisations of truly homoleptic acetonitrile Ln3+ complexes in solid state and in solution

Total halide abstraction from LnCl(3) by Ag[Al(OC(CF3)(3))(4)]/CH3CN has been confirmed for a series of lanthanide metal ions by the structural characterization of [Ln(CH3CN)(n)][Al(OC(CF3)(3))(4)](3) (n = 9, Ln(3+) = Nd, Eu, Gd, Dy; n = 8, Ln(3+) = Tm) complexes. Evidence for the very low coordinating ability of the [Al(OC(CF3)(3))(4)](-) anion towards Ln(3+) ions is provided in the solid state (X-ray, IR and Raman spectroscopy) and in anhydrous acetonitrile solution (conductivity, EPR and NMR measurements). In the solid state homoleptic nine-coordinated acetonitrile species are characteristic for lanthanides for the beginning (Nd) and the middle (Eu, Gd, Dy) of the Ln series, with a mono-capped square antiprismatic arrangement of the N donor atoms around the metal centres; while for those from the end of the series (Tm) eight-coordinated species are representative with a square antiprismatic arrangement. In anhydrous acetonitrile solution, conductivity measurements revealed 3: 1 electrolyte types for all compounds. EPR and F-19 NMR line broadening measurements attest lanthanide complexes free of any coordinating [Al(OC(CF3)(3))(4)](-) anion.