YSeF crystallizes in the monoclinic P2_1/m space group. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded to one Se(1), two equivalent Se(3), and three equivalent Se(2) atoms to form YSe6 octahedra that share corners with four equivalent Y(2)Se2F6 hexagonal bipyramids, corners with two equivalent Y(3)Se4F3 pentagonal bipyramids, edges with four equivalent Y(1)Se6 octahedra, and edges with two equivalent Y(4)Se4F3 pentagonal bipyramids. In the second Y site, Y(2) is bonded to one Se(1), one Se(2), one F(1), two equivalent F(3), and three equivalent F(4) atoms to form YSe2F6 hexagonal bipyramids that share corners with four equivalent Y(1)Se6 octahedra, corners with two equivalent Y(4)Se4F3 pentagonal bipyramids, edges with four equivalent Y(2)Se2F6 hexagonal bipyramids, and edges with two equivalent Y(3)Se4F3 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 55-59°. In the third Y site, Y(3) is bonded to one Se(3), three equivalent Se(4), one F(3), and two equivalent F(1) atoms to form distorted YSe4F3 pentagonal bipyramids that share corners with two equivalent Y(1)Se6 octahedra, corners with four equivalent Y(4)Se4F3 pentagonal bipyramids, edges with two equivalent Y(2)Se2F6 hexagonal bipyramids, and edges with four equivalent Y(3)Se4F3 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 59°. In the fourth Y site, Y(4) is bonded to one Se(3), one Se(4), two equivalent Se(1), and three equivalent F(2) atoms to form distorted YSe4F3 pentagonal bipyramids that share corners with two equivalent Y(2)Se2F6 hexagonal bipyramids, corners with four equivalent Y(3)Se4F3 pentagonal bipyramids, edges with two equivalent Y(1)Se6 octahedra, and edges with four equivalent Y(4)Se4F3 pentagonal bipyramids. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Y(1), one Y(2), and two equivalent Y(4) atoms. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Y(2) and three equivalent Y(1) atoms. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Y(3), one Y(4), and two equivalent Y(1) atoms. In the fourth Se site, Se(4) is bonded in a rectangular see-saw-like geometry to one Y(4) and three equivalent Y(3) atoms. There are four inequivalent F sites. In the first F site, F(1) is bonded in a trigonal planar geometry to one Y(2) and two equivalent Y(3) atoms. In the second F site, F(2) is bonded in a trigonal planar geometry to three equivalent Y(4) atoms. In the third F site, F(3) is bonded in a trigonal planar geometry to one Y(3) and two equivalent Y(2) atoms. In the fourth F site, F(4) is bonded in a trigonal planar geometry to three equivalent Y(2) atoms.
YSeF crystallizes in the monoclinic P2_1/m space group. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded to one Se(1), two equivalent Se(3), and three equivalent Se(2) atoms to form YSe6 octahedra that share corners with four equivalent Y(2)Se2F6 hexagonal bipyramids, corners with two equivalent Y(3)Se4F3 pentagonal bipyramids, edges with four equivalent Y(1)Se6 octahedra, and edges with two equivalent Y(4)Se4F3 pentagonal bipyramids. The Y(1)-Se(1) bond length is 2.84 Å. Both Y(1)-Se(3) bond lengths are 2.85 Å. There are two shorter (2.86 Å) and one longer (2.87 Å) Y(1)-Se(2) bond length. In the second Y site, Y(2) is bonded to one Se(1), one Se(2), one F(1), two equivalent F(3), and three equivalent F(4) atoms to form YSe2F6 hexagonal bipyramids that share corners with four equivalent Y(1)Se6 octahedra, corners with two equivalent Y(4)Se4F3 pentagonal bipyramids, edges with four equivalent Y(2)Se2F6 hexagonal bipyramids, and edges with two equivalent Y(3)Se4F3 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 55-59°. The Y(2)-Se(1) bond length is 2.82 Å. The Y(2)-Se(2) bond length is 2.85 Å. The Y(2)-F(1) bond length is 2.45 Å. Both Y(2)-F(3) bond lengths are 2.36 Å. There is one shorter (2.30 Å) and two longer (2.35 Å) Y(2)-F(4) bond lengths. In the third Y site, Y(3) is bonded to one Se(3), three equivalent Se(4), one F(3), and two equivalent F(1) atoms to form distorted YSe4F3 pentagonal bipyramids that share corners with two equivalent Y(1)Se6 octahedra, corners with four equivalent Y(4)Se4F3 pentagonal bipyramids, edges with two equivalent Y(2)Se2F6 hexagonal bipyramids, and edges with four equivalent Y(3)Se4F3 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 59°. The Y(3)-Se(3) bond length is 2.89 Å. There is one shorter (2.84 Å) and two longer (2.94 Å) Y(3)-Se(4) bond lengths. The Y(3)-F(3) bond length is 2.25 Å. Both Y(3)-F(1) bond lengths are 2.27 Å. In the fourth Y site, Y(4) is bonded to one Se(3), one Se(4), two equivalent Se(1), and three equivalent F(2) atoms to form distorted YSe4F3 pentagonal bipyramids that share corners with two equivalent Y(2)Se2F6 hexagonal bipyramids, corners with four equivalent Y(3)Se4F3 pentagonal bipyramids, edges with two equivalent Y(1)Se6 octahedra, and edges with four equivalent Y(4)Se4F3 pentagonal bipyramids. The Y(4)-Se(3) bond length is 2.88 Å. The Y(4)-Se(4) bond length is 2.81 Å. Both Y(4)-Se(1) bond lengths are 2.92 Å. There are two shorter (2.28 Å) and one longer (2.33 Å) Y(4)-F(2) bond length. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Y(1), one Y(2), and two equivalent Y(4) atoms. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Y(2) and three equivalent Y(1) atoms. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Y(3), one Y(4), and two equivalent Y(1) atoms. In the fourth Se site, Se(4) is bonded in a rectangular see-saw-like geometry to one Y(4) and three equivalent Y(3) atoms. There are four inequivalent F sites. In the first F site, F(1) is bonded in a trigonal planar geometry to one Y(2) and two equivalent Y(3) atoms. In the second F site, F(2) is bonded in a trigonal planar geometry to three equivalent Y(4) atoms. In the third F site, F(3) is bonded in a trigonal planar geometry to one Y(3) and two equivalent Y(2) atoms. In the fourth F site, F(4) is bonded in a trigonal planar geometry to three equivalent Y(2) atoms.