Low-Dimensional Organically Templated Uranium Fluorides (C5H14N2)2U2F12·2H2O and (C2H10N2)U2F10:  Hydrothermal Syntheses, Structures, and Magnetic Properties

• Published in: Chemistry of materials 2000-10, Vol.12 (10), p.3208-3213
• Main Authors: Almond, Philip M, Deakin, Laura, Porter, Melissa J, Mar, Arthur, Albrecht-Schmitt, Thomas E
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm000356+

Two new organically templated U(IV) fluorides, (C5H14N2)2U2F12·2H2O (AU1-1) and (C2H10N2)U2F10 (AU2-1), have been prepared from the reaction of UO3 with HF and homopiperazine (C5H12N2) at 200 °C in aqueous media. These compounds have been characterized by single-crystal X-ray diffraction, elemental analysis, and magnetic susceptibility measurements. Crystallographic data:  AU1-1, monoclinic, space group P21/c, a = 9.272(4) Å, b = 12.314(4) Å, c = 18.475(7) Å, β = 90.32(3)°, Z = 4; AU2-1, monoclinic, space group C2/c, a = 16.038(8) Å, b = 7.131(3) Å, c = 8.782(4) Å, β = 91.75(4)°, Z = 4. AU1-1 consists of face-sharing UF9 tricapped trigonal prisms that form one-dimensional chains that further hydrogen-bond with diprotonated homopiperazine and water molecules. AU2-1 forms, in part, from the cleavage of homopiperazine to yield diprotonated ethylenediamine, which serves to template the formation of uranium fluoride layers. These layers consist of edge- and corner-sharing UF9 tricapped trigonal prisms. The variable-temperature magnetic susceptibility of AU1-1 is consistent with antiferromagnetic interactions between U(IV) centers, with μeff(300 K) = 4.37 μB/f.u. and θ = −1.3 K. The magnetization of AU1-1 at 2 K displays an irreversible metamagnetic-like transition at H c = 3.60 T. The magnetic susceptibility for AU2-1 (μeff(300 K) = 4.58 μB/f.u.) with θ = +21 K suggests the presence of weak ferromagnetic interactions within the [U2F10]2- layers.