Materials Data on UCr4(H3O4)6 by Materials Project
UCr4(H3O4)6 crystallizes in the monoclinic C2/c space group. The structure is two-dimensional and consists of two UCr4(H3O4)6 sheets oriented in the (1, 0, 0) direction. U6+ is bonded to six O2- atoms to form UO6 octahedra that share corners with four CrO4 tetrahedra. There are a spread of U–O bond distances ranging from 1.82–2.33 Å. There are two inequivalent Cr6+ sites. In the first Cr6+ site, Cr6+ is bonded to four O2- atoms to form CrO4 tetrahedra that share a cornercorner with one UO6 octahedra. The corner-sharing octahedral tilt angles are 37°. There are a spread of Cr–O bond distances ranging from 1.59–1.74 Å. In the second Cr6+ site, Cr6+ is bonded to four O2- atoms to form CrO4 tetrahedra that share a cornercorner with one UO6 octahedra. The corner-sharing octahedral tilt angles are 35°. There are a spread of Cr–O bond distances ranging from 1.59–1.77 Å. There are nine inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.06 Å) and one longer (1.46 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.70 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.66 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.06 Å) and one longer (1.47 Å) H–O bond length. In the fifth H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.63 Å) H–O bond length. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eighth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.09 Å) and one longer (1.40 Å) H–O bond length. In the ninth 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 trigonal non-coplanar geometry to three H1+ atoms. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. 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 150 degrees geometry to one U6+ and one Cr6+ atom. In the sixth O2- site, O2- is bonded in a water-like geometry to one Cr6+ and one H1+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one Cr6+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr6+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one U6+, one Cr6+, and one H1+ atom. In the tenth O2- site, O2- is bonded in a single-bond geometry to one Cr6+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Cr6+ and two H1+ atoms. In the twelfth O2- site, O2- is bonded in a distorted single-bond geometry to one Cr6+ and one H1+ atom.