DOE OSTI2020
Rb21Tl7(O4Br21)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are four inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Rb–O bond lengths are 3.07 Å. In the second Rb1+ site, Rb1+ is bonded in a 6-coordinate geometry to six Br+0.29- atoms. There are two shorter (3.41 Å) and four longer (3.57 Å) Rb–Br bond lengths. In the third Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight Br+0.29- atoms. There are a spread of Rb–Br bond distances ranging from 3.38–3.82 Å. In the fourth Rb1+ site, Rb1+ is bonded in a 1-coordinate geometry to one O2- and seven Br+0.29- atoms. The Rb–O bond length is 2.84 Å. There are a spread of Rb–Br bond distances ranging from 3.56–3.67 Å. There are three inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded in an octahedral geometry to six Br+0.29- atoms. There are two shorter (2.60 Å) and four longer (2.96 Å) Tl–Br bond lengths. In the second Tl1+ site, Tl1+ is bonded in an octahedral geometry to six Br+0.29- atoms. There are two shorter (2.71 Å) and four longer (2.84 Å) Tl–Br bond lengths. In the third Tl1+ site, Tl1+ is bonded in an octahedral geometry to six Br+0.29- atoms. There are a spread of Tl–Br bond distances ranging from 2.71–3.07 Å. O2- is bonded in a 2-coordinate geometry to two Rb1+ and two equivalent Br+0.29- atoms. Both O–Br bond lengths are 3.02 Å. There are seven inequivalent Br+0.29- sites. In the first Br+0.29- site, Br+0.29- is bonded to five Rb1+ and one Tl1+ atom to form distorted BrRb5Tl octahedra that share corners with two equivalent BrRb5Tl octahedra, corners with four equivalent BrRb4Tl square pyramids, a cornercorner with one BrRb4Tl trigonal bipyramid, edges with two equivalent BrRb4Tl square pyramids, faces with two equivalent BrRb5Tl octahedra, faces with two equivalent BrRb4Tl square pyramids, and a faceface with one BrRb4Tl trigonal bipyramid. The corner-sharing octahedra tilt angles range from 0–39°. In the second Br+0.29- site, Br+0.29- is bonded to four Rb1+ and one Tl1+ atom to form distorted BrRb4Tl square pyramids that share corners with four equivalent BrRb5Tl octahedra, a cornercorner with one BrRb4Tl square pyramid, corners with two equivalent BrRb4Tl trigonal bipyramids, edges with two equivalent BrRb5Tl octahedra, and edges with four BrRb4Tl square pyramids. The corner-sharing octahedra tilt angles range from 46–48°. In the third Br+0.29- site, Br+0.29- is bonded in a 1-coordinate geometry to two equivalent Rb1+, one Tl1+, and two equivalent O2- atoms. In the fourth Br+0.29- site, Br+0.29- is bonded in a 4-coordinate geometry to three Rb1+ and one Tl1+ atom. In the fifth Br+0.29- site, Br+0.29- is bonded in a single-bond geometry to one Tl1+ atom. In the sixth Br+0.29- site, Br+0.29- is bonded to four Rb1+ and one Tl1+ atom to form distorted BrRb4Tl trigonal bipyramids that share corners with two equivalent BrRb5Tl octahedra, corners with six BrRb4Tl square pyramids, a cornercorner with one BrRb4Tl trigonal bipyramid, edges with two equivalent BrRb4Tl trigonal bipyramids, and faces with two equivalent BrRb5Tl octahedra. The corner-sharing octahedral tilt angles are 34°. In the seventh Br+0.29- site, Br+0.29- is bonded to four Rb1+ and one Tl1+ atom to form distorted BrRb4Tl square pyramids that share a cornercorner with one BrRb4Tl square pyramid, corners with two equivalent BrRb4Tl trigonal bipyramids, edges with four equivalent BrRb4Tl square pyramids, and faces with four equivalent BrRb5Tl octahedra.