Cs3Sb2Br9 crystallizes in the trigonal P-3m1 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to three equivalent Br(2) and nine equivalent Br(1) atoms to form CsBr12 cuboctahedra that share corners with three equivalent Cs(2)Br12 cuboctahedra, corners with nine equivalent Cs(1)Br12 cuboctahedra, faces with three equivalent Cs(1)Br12 cuboctahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, and faces with five equivalent Sb(1)Br6 octahedra. In the second Cs site, Cs(2) is bonded to six equivalent Br(1) and six equivalent Br(2) atoms to form CsBr12 cuboctahedra that share corners with six equivalent Cs(1)Br12 cuboctahedra, corners with six equivalent Cs(2)Br12 cuboctahedra, faces with six equivalent Cs(1)Br12 cuboctahedra, and faces with six equivalent Sb(1)Br6 octahedra. Sb(1) is bonded to three equivalent Br(1) and three equivalent Br(2) atoms to form SbBr6 octahedra that share corners with three equivalent Sb(1)Br6 octahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, and faces with five equivalent Cs(1)Br12 cuboctahedra. The corner-sharing octahedra are not tilted. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded to one Cs(2), three equivalent Cs(1), and one Sb(1) atom to form distorted BrCs4Sb square pyramids that share corners with eight equivalent Br(2)Cs4Sb2 octahedra, corners with thirteen equivalent Br(1)Cs4Sb square pyramids, edges with two equivalent Br(2)Cs4Sb2 octahedra, edges with six equivalent Br(1)Cs4Sb square pyramids, faces with two equivalent Br(2)Cs4Sb2 octahedra, and faces with two equivalent Br(1)Cs4Sb square pyramids. The corner-sharing octahedral tilt angles range from 1-60°. In the second Br site, Br(2) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Sb(1) atoms to form BrCs4Sb2 octahedra that share corners with six equivalent Br(2)Cs4Sb2 octahedra, corners with sixteen equivalent Br(1)Cs4Sb square pyramids, edges with four equivalent Br(1)Cs4Sb square pyramids, faces with four equivalent Br(2)Cs4Sb2 octahedra, and faces with four equivalent Br(1)Cs4Sb square pyramids. The corner-sharing octahedral tilt angles range from 0-60°.
Cs3Sb2Br9 crystallizes in the trigonal P-3m1 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to three equivalent Br(2) and nine equivalent Br(1) atoms to form CsBr12 cuboctahedra that share corners with three equivalent Cs(2)Br12 cuboctahedra, corners with nine equivalent Cs(1)Br12 cuboctahedra, faces with three equivalent Cs(1)Br12 cuboctahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, and faces with five equivalent Sb(1)Br6 octahedra. All Cs(1)-Br(2) bond lengths are 3.96 Å. There are three shorter (3.98 Å) and six longer (3.99 Å) Cs(1)-Br(1) bond lengths. In the second Cs site, Cs(2) is bonded to six equivalent Br(1) and six equivalent Br(2) atoms to form CsBr12 cuboctahedra that share corners with six equivalent Cs(1)Br12 cuboctahedra, corners with six equivalent Cs(2)Br12 cuboctahedra, faces with six equivalent Cs(1)Br12 cuboctahedra, and faces with six equivalent Sb(1)Br6 octahedra. All Cs(2)-Br(1) bond lengths are 4.05 Å. All Cs(2)-Br(2) bond lengths are 3.99 Å. Sb(1) is bonded to three equivalent Br(1) and three equivalent Br(2) atoms to form SbBr6 octahedra that share corners with three equivalent Sb(1)Br6 octahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, and faces with five equivalent Cs(1)Br12 cuboctahedra. The corner-sharing octahedra are not tilted. All Sb(1)-Br(1) bond lengths are 2.67 Å. All Sb(1)-Br(2) bond lengths are 2.95 Å. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded to one Cs(2), three equivalent Cs(1), and one Sb(1) atom to form distorted BrCs4Sb square pyramids that share corners with eight equivalent Br(2)Cs4Sb2 octahedra, corners with thirteen equivalent Br(1)Cs4Sb square pyramids, edges with two equivalent Br(2)Cs4Sb2 octahedra, edges with six equivalent Br(1)Cs4Sb square pyramids, faces with two equivalent Br(2)Cs4Sb2 octahedra, and faces with two equivalent Br(1)Cs4Sb square pyramids. The corner-sharing octahedral tilt angles range from 1-60°. In the second Br site, Br(2) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Sb(1) atoms to form BrCs4Sb2 octahedra that share corners with six equivalent Br(2)Cs4Sb2 octahedra, corners with sixteen equivalent Br(1)Cs4Sb square pyramids, edges with four equivalent Br(1)Cs4Sb square pyramids, faces with four equivalent Br(2)Cs4Sb2 octahedra, and faces with four equivalent Br(1)Cs4Sb square pyramids. The corner-sharing octahedral tilt angles range from 0-60°.