DOI: 10.17188/1728294
title: Materials Data on CaU2Si2(HO3)4 by Materials Project

description: CaU2Si2(HO3)4 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Ca2+ is bonded in a 6-coordinate geometry to two H1+ and four O2- atoms. There are one shorter (2.49 Å) and one longer (2.58 Å) Ca–H bond lengths. There are a spread of Ca–O bond distances ranging from 2.18–2.58 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 equivalent 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 1.83–2.55 Å. In the second U5+ site, U5+ is bonded to seven O2- atoms to form distorted UO7 pentagonal bipyramids that share corners with three equivalent 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 1.80–2.55 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 equivalent UO7 pentagonal bipyramids and an edgeedge with one UO7 pentagonal bipyramid. There are a spread of Si–O bond distances ranging from 1.61–1.72 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent UO7 pentagonal bipyramids and an edgeedge with one UO7 pentagonal bipyramid. There are a spread of Si–O bond distances ranging from 1.57–1.73 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one Ca2+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one Ca2+ atom. In the third 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 fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one U5+, one Si4+, and one H1+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Ca2+ and one Si4+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent U5+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent U5+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a distorted linear geometry to one U5+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Si4+, and one H1+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one U5+ 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 distorted bent 150 degrees geometry to one Ca2+ and one U5+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent U5+ and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Ca2+ and one U5+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent U5+ and one Si4+ atom.