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 D_3d 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.