Materials Data on U8CrSe17 by Materials Project

U8CrSe17 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent U+3.88+ sites. In the first U+3.88+ site, U+3.88+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of U–Se bond distances ranging from 2.88–3.04 Å. In the second U+3.88+ site, U+3.88+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of U–Se bond distances ranging from 2.86–2.95 Å. In the third U+3.88+ site, U+3.88+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of U–Se bond distances ranging from 2.81–3.10 Å. Cr3+ is bonded in an octahedral geometry to six Se2- atoms. There are two shorter (2.43 Å) and four longer (2.54 Å) Cr–Se bond lengths. There are seven inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to four U+3.88+ atoms to form distorted SeU4 trigonal pyramids that share corners with two equivalent SeU6 octahedra, corners with six equivalent SeU3Cr tetrahedra, edges with two equivalent SeU3Cr tetrahedra, and an edgeedge with one SeU4 trigonal pyramid. The corner-sharing octahedral tilt angles are 38°. In the second Se2- site, Se2- is bonded to six U+3.88+ atoms to form SeU6 octahedra that share corners with four equivalent SeU3Cr tetrahedra and corners with four equivalent SeU4 trigonal pyramids. In the third Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to four U+3.88+ atoms. In the fourth Se2- site, Se2- is bonded to three U+3.88+ and one Cr3+ atom to form distorted SeU3Cr tetrahedra that share a cornercorner with one SeU6 octahedra, corners with five equivalent SeU3Cr tetrahedra, corners with three equivalent SeU4 trigonal pyramids, edges with two equivalent SeU3Cr tetrahedra, and an edgeedge with one SeU4 trigonal pyramid. The corner-sharing octahedral tilt angles are 53°. In the fifth Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to four U+3.88+ atoms. In the sixth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three U+3.88+ and one Cr3+ atom. In the seventh Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to four U+3.88+ atoms.