Hydrothermal synthesis, crystal structure, and characterization of a new pseudo-two-dimensional uranyl oxyfluoride, [N(C2H5)4]2[(UO2)4(OH2)3F10]

A new uranyl oxyfluoride, [N(C2H5)4]2[(UO2)4(OH2)3F10] has been synthesized by a hydrothermal reaction technique using (C2H5)4NBr, UO2(OCOCH3)2·2H2O, and HF as reagents. The structure of [N(C2H5)4]2[(UO2)4(OH2)3F10] has been determined by a single-crystal X-ray diffraction technique. [N(C2H5)4]2[(UO2)4(OH2)3F10] crystallizes in the monoclinic space group P21/n   (No. 14), with a=13.852(3)Å, b=15.532(3)Å, c=16.481(3)Å, β=98.88(3)°β=98.88(3)°, V=3503.4(12)Å3, and Z=4Z=4. [N(C2H5)4]2[(UO2)4(OH2)3F10] reveals a novel pseudo-two-dimensional crystal structure that is composed of UO2F5, UO3F4, and UO4F3 pentagonal bipyramids. Each uranyl pentagonal bipyramid shares edges and corners through F atoms to form a six-membered ring. The rings are further interconnected to generate infinite strips running along the b-axis. [N(C2H5)4]2[(UO2)4(OH2)3F10] has been further characterized by elemental analysis, bond valence calculations, Infrared and Raman spectroscopy, and thermogravimetric analysis.

Graphical abstractORTEP (50% probability ellipsoids) drawing of [N(C2H5)4]2[(UO2)4(OH2)3F10] in the ab-plane. Note the pentagonal bipyramidal environments of U6+ cations to form a novel six-membered ring .Figure optionsDownload full-size imageDownload as PowerPoint slide