DOI: 10.17188/1685590
title: Materials Data on CaU2Si2(HO3)4 by Materials Project

description: (CaU2Si2(HO4)3)2H2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional and consists of four hydrogen molecules and one CaU2Si2(HO4)3 framework. In the CaU2Si2(HO4)3 framework, Ca2+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ca–O bond distances ranging from 2.15–2.33 Å. There are two inequivalent U5+ sites. In the first U5+ site, U5+ is bonded to seven O2- atoms to form distorted UO7 pentagonal bipyramids that share corners with three SiO4 tetrahedra, edges with two equivalent UO7 pentagonal bipyramids, and an edgeedge with one SiO4 tetrahedra. There are a spread of U–O bond distances ranging from 1.83–2.60 Å. In the second U5+ site, U5+ is bonded to seven O2- atoms to form distorted UO7 pentagonal bipyramids that share corners with three SiO4 tetrahedra, edges with two equivalent UO7 pentagonal bipyramids, and an edgeedge with one SiO4 tetrahedra. There are a spread of U–O bond distances ranging from 1.86–2.54 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three UO7 pentagonal bipyramids and an edgeedge with one UO7 pentagonal bipyramid. There are a spread of Si–O bond distances ranging from 1.62–1.69 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three UO7 pentagonal bipyramids and an edgeedge with one UO7 pentagonal bipyramid. There are a spread of Si–O bond distances ranging from 1.58–1.73 Å. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Ca2+ and one U5+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one U5+, one Si4+, and one H1+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one U5+, one Si4+, and one H1+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two U5+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ca2+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to two U5+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to two U5+ and one Si4+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one U5+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to two U5+ and one Si4+ atom. In the tenth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ca2+ and one U5+ atom. In the eleventh O2- site, O2- is bonded in a bent 120 degrees geometry to one Si4+ and one H1+ atom. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ca2+ and one U5+ atom.