Materials Data on UH2Se2O9 by Materials Project
UH2Se2O9 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. U6+ is bonded to seven O2- atoms to form distorted UO7 pentagonal bipyramids that share corners with four equivalent SeO4 tetrahedra. There are a spread of U–O bond distances ranging from 1.80–2.49 Å. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. Se5+ is bonded to four O2- atoms to form distorted SeO4 tetrahedra that share corners with two equivalent UO7 pentagonal bipyramids and corners with two equivalent SeO4 tetrahedra. There are a spread of Se–O bond distances ranging from 1.69–2.32 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one U6+ and one Se5+ atom. In the second O2- site, O2- is bonded in a water-like geometry to one U6+ and two equivalent H1+ atoms. In the third O2- site, O2- is bonded in a linear geometry to one U6+ and one Se5+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one U6+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Se5+ atoms.