Single Crystal Structure Precludes Predicted Ferroelectricity of Uranium Trifluoride, UF₃

Single crystals of uranium trifluoride, UF₃, were obtained for the first time via gas-phase crystallization, enabling the resolution of its crystal structure using single-crystal X-ray diffraction (SCXRD). The study reveals that UF₃ crystallizes isotypic to the tysonite structure type in the trigonal space group <i>P</i>3̅<i>c</i>1 (No. 165, <i>hP</i>24, <i>gfda</i>) with lattice parameters <i>a</i> = 7.1510(2), <i>c</i> = 7.3230(4) Å, and <i>V</i> = 324.30(³) ų, <i>Z</i> = 6, at <i>T</i> = 100 K, resolving long-standing structure model ambiguities from prior studies based on powder diffraction. Merohedral twinning complicates the diffraction data by simulating the wrong Laue class 6/<i>mmm</i>. Complementary quantum chemical calculations support the findings from this experiment, confirming its local energetic minimum. The inversion center in the crystal structure of UF₃ precludes the previously predicted ferroelectricity.