Optical and magnetic properties of uranium borohydride and tetrakismethylborohydride

摘要

The U(BD4)4/Hf(BD4)4optical spectrum reported by Bernstein and Keiderling has been reanalyzed. All 19 allowed transitions have been identified. The crystal field is sim;2.5 times as strong as that ofthinsp; U4+/ThBr4, but the values of theFkand zgr; parameters are nearly the same. The magnetic susceptibility of the structurally related molecule U(BH3CH3)4has been measured from 2ndash;330 K. Using the eigenvectors from the optical analysis, the magnetic data can be fit with an orbital reduction factork=0.85. For U(BD4)4/Hf(BD4)4k=zgr;/zgr;free ion=0.91.