Cs3Cr2Br9 crystallizes in the hexagonal P6_3/mmc 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 six equivalent Cs(1)Br12 cuboctahedra, corners with three equivalent Cr(1)Br6 octahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, faces with four equivalent Cs(1)Br12 cuboctahedra, and faces with four equivalent Cr(1)Br6 octahedra. The corner-sharing octahedral tilt angles are 14°. 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 Cr(1)Br6 octahedra. Cr(1) is bonded to three equivalent Br(1) and three equivalent Br(2) atoms to form CrBr6 octahedra that share corners with three equivalent Cs(1)Br12 cuboctahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, faces with four equivalent Cs(1)Br12 cuboctahedra, and  a faceface with one Cr(1)Br6 octahedra. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded in a distorted single-bond geometry to one Cs(2), three equivalent Cs(1), and one Cr(1) atom. In the second Br site, Br(2) is bonded in a 2-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Cr(1) atoms.
Cs3Cr2Br9 crystallizes in the hexagonal P6_3/mmc 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 six equivalent Cs(1)Br12 cuboctahedra, corners with three equivalent Cr(1)Br6 octahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, faces with four equivalent Cs(1)Br12 cuboctahedra, and faces with four equivalent Cr(1)Br6 octahedra. The corner-sharing octahedral tilt angles are 14°. All Cs(1)-Br(2) bond lengths are 4.16 Å. There are three shorter (3.77 Å) and six longer (3.83 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 Cr(1)Br6 octahedra. All Cs(2)-Br(1) bond lengths are 3.81 Å. All Cs(2)-Br(2) bond lengths are 3.82 Å. Cr(1) is bonded to three equivalent Br(1) and three equivalent Br(2) atoms to form CrBr6 octahedra that share corners with three equivalent Cs(1)Br12 cuboctahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, faces with four equivalent Cs(1)Br12 cuboctahedra, and  a faceface with one Cr(1)Br6 octahedra. All Cr(1)-Br(1) bond lengths are 2.45 Å. All Cr(1)-Br(2) bond lengths are 2.60 Å. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded in a distorted single-bond geometry to one Cs(2), three equivalent Cs(1), and one Cr(1) atom. In the second Br site, Br(2) is bonded in a 2-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Cr(1) atoms.