Synthesis, structure determination, and infrared spectroscopy of (NpO 2) 2(SO 4)(H 2O) 4: Prevalence of cation–cation interactions and cationic nets in neptunyl sulfate compounds

• Published in: Journal of solid state chemistry Vol. 182; no. 1; pp. 43 - 48
• Main Authors: Forbes, T.Z., Burns, P.C.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 2009
• Subjects: Actinide; Crystal structure; Neptunium; Single crystal X-ray diffraction; Sulfate; Single crystal X-ray diffraction; Actinide; Sulfate; Neptunium; Crystal structure
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2008.08.032

The compound (NpO 2) 2(SO 4)(H 2O) 4 was synthesized by evaporation of a Np 5+ sulfate solution. The crystal structure was determined using single crystal X-ray diffraction and refined to an R 1=0.0310. (NpO 2) 2(SO 4)(H 2O) 4 crystallizes in triclinic space group P-1, a=8.1102(7) Å, b=8.7506(7) Å, c=16.234(1) Å, α=90.242(2)°, β=92.855(2)°, γ=113.067(2)°, V=1058.3(2) Å 3, and Z=2. The structure contains neptunyl pentagonal bipyramids that share vertices through cation–cation interactions to form a sheet or cationic net. The sheet is decorated on each side by vertex sharing with sulfate tetrahedra, and adjacent sheets are linked together through hydrogen bonding. A graphical representation of (NpO 2) 2(SO 4)(H 2O) 4 was constructed to facilitate the structural comparison to similar Np 5+ compounds. The prevalence of the cationic nets in neptunyl sulfate compounds related to the overall stability of the structure is also discussed. (NpO 2) 2(SO 4)(H 2O) 4 was synthesized by hydrothermal methods and its structure determined. A graphical representation of the compound was constructed to facilitate the structural comparison to similar Np 5+ compounds and the prevalence of the cationic nets in neptunyl sulfate compounds related to the overall stability of the structure is discussed.