Single-crystal magnetic properties of lanthanide complexes. Part VII. Hexakis(antipyrine)europium(III) tri-iodide
Abstract
The principal and average magnetic moments of hexakis(antipyrine)europium(III) tri-iodide (antipyrine is 2,3-dimethyl-1-phenyl-Δ3-pyrazolin-5-one) have been measured in the temperature range 300–80 K. Approximate values for the powder susceptibilities have also been determined down to 4 K. These are interpreted within a point-change crystal-field model of D3d symmetry, using the free-ion ground term, corrected for the effects of intermediate coupling, as basis. However, the restricted basis of 7F0+7F1+7F2+7F3 was found to be sufficient for present purposes. Sixth-order crystal-field terms cannot operate in the first three states so that no value for ρ6 could be estimated. Estimates of ρ4 depend critically upon the energy levels of the very low-lying state of europium(III), so that only a relationship between these has been established. Magnetic anisotropies, however, have fixed a value of A20〈r2〉, related to the second-order potential, of ca. 250 cm–1.