DOE OSTI2020
Y16Se16F15 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are sixteen inequivalent Y sites. In the first Y site, Y is bonded to four Se and three F atoms to form a mixture of distorted edge and corner-sharing YSe4F3 pentagonal bipyramids. There are a spread of Y–Se bond distances ranging from 2.85–2.94 Å. There are two shorter (2.32 Å) and one longer (2.37 Å) Y–F bond lengths. In the second Y site, Y is bonded to four Se and three F atoms to form a mixture of distorted edge and corner-sharing YSe4F3 pentagonal bipyramids. There are two shorter (2.86 Å) and two longer (2.95 Å) Y–Se bond lengths. There are two shorter (2.31 Å) and one longer (2.36 Å) Y–F bond lengths. In the third Y site, Y is bonded to four Se and three F atoms to form distorted YSe4F3 pentagonal bipyramids that share corners with two equivalent YSe2F5 hexagonal pyramids, corners with four YSe4F3 pentagonal bipyramids, edges with two equivalent YSe6 octahedra, and edges with four YSe4F3 pentagonal bipyramids. There are a spread of Y–Se bond distances ranging from 2.85–2.94 Å. There are two shorter (2.30 Å) and one longer (2.36 Å) Y–F bond lengths. In the fourth Y site, Y is bonded to four Se and three F atoms to form distorted YSe4F3 pentagonal bipyramids that share corners with two equivalent YSe2F4 octahedra, corners with four YSe4F3 pentagonal bipyramids, edges with two equivalent YSe6 octahedra, and edges with four YSe4F3 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 55°. There are a spread of Y–Se bond distances ranging from 2.85–2.94 Å. There are two shorter (2.31 Å) and one longer (2.36 Å) Y–F bond lengths. In the fifth Y site, Y is bonded to two Se and four F atoms to form distorted YSe2F4 octahedra that share corners with two equivalent YSe2F5 hexagonal pyramids, corners with six YSe2F4 octahedra, corners with two equivalent YSe4F3 pentagonal bipyramids, and edges with two equivalent YSe4F3 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 54–59°. Both Y–Se bond lengths are 2.85 Å. There are a spread of Y–F bond distances ranging from 2.24–2.42 Å. In the sixth Y site, Y is bonded to two Se and five F atoms to form distorted YSe2F5 hexagonal pyramids that share corners with six YSe6 octahedra, corners with two equivalent YSe4F3 pentagonal bipyramids, edges with two equivalent YSe2F5 hexagonal pyramids, and edges with two equivalent YSe4F3 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 55–61°. There are one shorter (2.82 Å) and one longer (2.87 Å) Y–Se bond lengths. There are a spread of Y–F bond distances ranging from 2.36–2.50 Å. In the seventh Y site, Y is bonded to four Se and three F atoms to form a mixture of distorted edge and corner-sharing YSe4F3 pentagonal bipyramids. There are a spread of Y–Se bond distances ranging from 2.86–2.94 Å. There are two shorter (2.30 Å) and one longer (2.36 Å) Y–F bond lengths. In the eighth Y site, Y is bonded to four Se and three F atoms to form a mixture of distorted edge and corner-sharing YSe4F3 pentagonal bipyramids. There are a spread of Y–Se bond distances ranging from 2.85–2.94 Å. There are two shorter (2.31 Å) and one longer (2.37 Å) Y–F bond lengths. In the ninth Y site, Y is bonded to four Se and three F atoms to form a mixture of distorted edge and corner-sharing YSe4F3 pentagonal bipyramids. There are a spread of Y–Se bond distances ranging from 2.85–2.94 Å. There are two shorter (2.31 Å) and one longer (2.37 Å) Y–F bond lengths. In the tenth Y site, Y is bonded to four Se and three F atoms to form a mixture of distorted edge and corner-sharing YSe4F3 pentagonal bipyramids. There are a spread of Y–Se bond distances ranging from 2.84–2.93 Å. There are two shorter (2.31 Å) and one longer (2.37 Å) Y–F bond lengths. In the eleventh Y site, Y is bonded to four Se and three F atoms to form distorted YSe4F3 pentagonal bipyramids that share corners with two equivalent YSe6 octahedra, corners with four YSe4F3 pentagonal bipyramids, edges with two equivalent YSe2F5 hexagonal pyramids, and edges with four YSe4F3 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 58°. There are a spread of Y–Se bond distances ranging from 2.85–2.97 Å. There are two shorter (2.29 Å) and one longer (2.33 Å) Y–F bond lengths. In the twelfth Y site, Y is bonded to four Se and three F atoms to form distorted YSe4F3 pentagonal bipyramids that share corners with two equivalent YSe6 octahedra, corners with four YSe4F3 pentagonal bipyramids, edges with two equivalent YSe2F4 octahedra, and edges with four YSe4F3 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 58°. There are a spread of Y–Se bond distances ranging from 2.84–2.96 Å. There are two shorter (2.30 Å) and one longer (2.39 Å) Y–F bond lengths. In the thirteenth Y site, Y is bonded to six Se atoms to form YSe6 octahedra that share corners with two equivalent YSe2F5 hexagonal pyramids, corners with two equivalent YSe2F4 octahedra, corners with two equivalent YSe4F3 pentagonal bipyramids, edges with four YSe6 octahedra, and edges with two equivalent YSe4F3 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 56–59°. There are a spread of Y–Se bond distances ranging from 2.85–2.88 Å. In the fourteenth Y site, Y is bonded to six Se atoms to form YSe6 octahedra that share corners with two equivalent YSe2F5 hexagonal pyramids, corners with two equivalent YSe2F4 octahedra, corners with two equivalent YSe4F3 pentagonal bipyramids, edges with four YSe6 octahedra, and edges with two equivalent YSe4F3 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 58°. There are a spread of Y–Se bond distances ranging from 2.85–2.92 Å. In the fifteenth Y site, Y is bonded to four Se and three F atoms to form a mixture of distorted edge and corner-sharing YSe4F3 pentagonal bipyramids. There are a spread of Y–Se bond distances ranging from 2.86–2.94 Å. There are two shorter (2.31 Å) and one longer (2.37 Å) Y–F bond lengths. In the sixteenth Y site, Y is bonded to four Se and three F atoms to form a mixture of distorted edge and corner-sharing YSe4F3 pentagonal bipyramids. There are two shorter (2.87 Å) and two longer (2.94 Å) Y–Se bond lengths. There are two shorter (2.31 Å) and one longer (2.37 Å) Y–F bond lengths. There are sixteen inequivalent Se sites. In the first Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the second Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the third Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the fourth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the fifth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the sixth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the seventh Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the eighth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the ninth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the tenth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the eleventh Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the twelfth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the thirteenth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the fourteenth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the fifteenth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the sixteenth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. There are fifteen inequivalent F sites. In the first F site, F is bonded in a trigonal planar geometry to three Y atoms. In the second F site, F is bonded in a trigonal planar geometry to three Y atoms. In the third F site, F is bonded in a trigonal planar geometry to three Y atoms. In the fourth F site, F is bonded in a trigonal planar geometry to three Y atoms. In the fifth F site, F is bonded in a trigonal planar geometry to three Y atoms. In the sixth F site, F is bonded in a trigonal planar geometry to three Y atoms. In the seventh F site, F is bonded in a trigonal planar geometry to three Y atoms. In the eighth F site, F is bonded in a trigonal planar geometry to three Y atoms. In the ninth F site, F is bonded in a trigonal planar geometry to three Y atoms. In the tenth F site, F is bonded in a trigonal planar geometry to three Y atoms. In the eleventh F site, F is bonded in a trigonal planar geometry to three Y atoms. In the twelfth F site, F is bonded in a trigonal planar geometry to three Y atoms. In the thirteenth F site, F is bonded in a trigonal planar geometry to three Y atoms. In the fourteenth F site, F is bonded in a trigonal planar geometry to three Y atoms. In the fifteenth F site, F is bonded in a trigonal planar geometry to three Y atoms.