CsAuBr3 crystallizes in the tetragonal I4/mmm space group. Cs(1) is bonded to four equivalent Br(1) and eight equivalent Br(2) atoms to form CsBr12 cuboctahedra that share corners with twelve equivalent Cs(1)Br12 cuboctahedra, faces with six equivalent Cs(1)Br12 cuboctahedra, and faces with four equivalent Au(2)Br6 octahedra. There are two inequivalent Au sites. In the first Au site, Au(1) is bonded in a square co-planar geometry to four equivalent Br(2) atoms. In the second Au site, Au(2) is bonded to two equivalent Br(1) and four equivalent Br(2) atoms to form AuBr6 octahedra that share faces with eight equivalent Cs(1)Br12 cuboctahedra. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded in a distorted single-bond geometry to four equivalent Cs(1) and one Au(2) atom. In the second Br site, Br(2) is bonded to four equivalent Cs(1), one Au(1), and one Au(2) atom to form a mixture of distorted face, corner, and edge-sharing BrCs4Au2 octahedra. The corner-sharing octahedral tilt angles range from 0-59°.
CsAuBr3 crystallizes in the tetragonal I4/mmm space group. Cs(1) is bonded to four equivalent Br(1) and eight equivalent Br(2) atoms to form CsBr12 cuboctahedra that share corners with twelve equivalent Cs(1)Br12 cuboctahedra, faces with six equivalent Cs(1)Br12 cuboctahedra, and faces with four equivalent Au(2)Br6 octahedra. All Cs(1)-Br(1) bond lengths are 3.93 Å. All Cs(1)-Br(2) bond lengths are 3.99 Å. There are two inequivalent Au sites. In the first Au site, Au(1) is bonded in a square co-planar geometry to four equivalent Br(2) atoms. All Au(1)-Br(2) bond lengths are 2.49 Å. In the second Au site, Au(2) is bonded to two equivalent Br(1) and four equivalent Br(2) atoms to form AuBr6 octahedra that share faces with eight equivalent Cs(1)Br12 cuboctahedra. Both Au(2)-Br(1) bond lengths are 2.44 Å. All Au(2)-Br(2) bond lengths are 3.03 Å. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded in a distorted single-bond geometry to four equivalent Cs(1) and one Au(2) atom. In the second Br site, Br(2) is bonded to four equivalent Cs(1), one Au(1), and one Au(2) atom to form a mixture of distorted face, corner, and edge-sharing BrCs4Au2 octahedra. The corner-sharing octahedral tilt angles range from 0-59°.