[Hg5O2(OH)4][(UO2)2(AsO4)2]: A complex mercury(II) uranyl arsenate

Under mild hydrothermal conditions UO2(NO3)2·6H2O, Hg2(NO3)2·2H2O, and Na2HAsO4·7H2O react to form [Hg5O2(OH)4][(UO2)2(AsO4)2] (HgUAs-1). Single crystal X-ray diffraction experiments reveal that HgUAs-1 possesses a pseudo-layered structure consisting of two types of layers: ∞2[Hg5O2(OH)4]2+ and ∞2[(UO2)2(AsO4)2]2-. The ∞2[Hg5O2(OH)4]2+ layers are complex, and contain three crystallographically unique Hg centers. The coordination environments and bond–valence sum calculations indicate that the Hg centers are divalent. The ∞2[(UO2)2(AsO4)2]2- layers belong to the Johannite topological family. The ∞2[Hg5O2(OH)4]2+ and ∞2[(UO2)2(AsO4)2]2- layers are linked to each other through μ2-O bridges that include Hg⋯O=U=O interactions.

A depiction of the coordination environments for mercury in [Hg5O2(OH)4][(UO2)2(AsO4)2] (HgUAs-1).Figure optionsDownload as PowerPoint slide