• Karttunen, Antti J.
• Kraus, Florian
• Woidy, Patrick

Abstract

<p>Uranyl chloride UO2Cl2 and uranyl fluoride UO2F2 react with dry liquid ammonia under the formation of traffic-green crystals of pentaammine dioxido uranium(VI) dichloride ammonia (1/1) [UO2(NH3)5]Cl2 center dot NH3 (1) and sulfur-yellow crystals of triammine difluorido dioxido uranium(VI) ammonia (2/2) [UO2F2(NH3)3]2 center dot 2NH3 (2), respectively. Low-temperature X-ray structure analyses on single crystals of the two compounds were conducted. Compound 1 crystallizes in the orthorhombic space group Cmcm with a = 12.7865(2), b = 10.5106(2), c = 8.7089(2) angstrom, V = 1170.45(4) angstrom 3 at 123 K with Z = 4. Compound 2 crystallizes in the orthorhombic space group Pnma with a = 20.8451(5), b = 9.1267(2), c = 8.3371(2) angstrom, V = 1586(6) angstrom 3 at 123 K with Z = 4. Further investigations on the room-temperature decomposition products of compounds 1 and 2 by Raman and IR spectroscopy, TGA MS and X-ray powder diffraction measurements and deuteration studies led to the identification of triammine dichlorido dioxido uranium(VI) UO2Cl2(NH3)3 (3) and triammine difluorido dioxido uranium(VI) UO2F2(NH3)3 (4) in the form of fern-green and zinc-yellow powders. Quantum chemical studies at the DFT-PBE0/TZVP level of theory support the experimental observations andalso show that the O=U=O triple bonding in the [UO2F2(NH3)3] molecule of compound 2 is weaker in comparison to the one in the [UO2(NH3)5]2+ dication of compound 1.</p>

Topics

• impedance spectroscopy
• compound
• single crystal
• theory
• zinc
• mass spectrometry
• thermogravimetry
• density functional theory
• decomposition
• space group
• infrared spectroscopy
• Uranium