Cs3Mo2O7Br crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to nine equivalent O(2) and one Br(1) atom. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to six equivalent O(2) and three equivalent Br(1) atoms. Mo(1) is bonded to one O(1) and three equivalent O(2) atoms to form corner-sharing MoO4 tetrahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Mo(1) atoms. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Cs(2), three equivalent Cs(1), and one Mo(1) atom. Br(1) is bonded to two equivalent Cs(1) and three equivalent Cs(2) atoms to form corner-sharing BrCs5 trigonal bipyramids.
Cs3Mo2O7Br crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to nine equivalent O(2) and one Br(1) atom. There are three shorter (3.29 Å) and six longer (3.46 Å) Cs(1)-O(2) bond lengths. The Cs(1)-Br(1) bond length is 3.46 Å. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to six equivalent O(2) and three equivalent Br(1) atoms. All Cs(2)-O(2) bond lengths are 3.34 Å. All Cs(2)-Br(1) bond lengths are 3.84 Å. Mo(1) is bonded to one O(1) and three equivalent O(2) atoms to form corner-sharing MoO4 tetrahedra. The Mo(1)-O(1) bond length is 1.92 Å. All Mo(1)-O(2) bond lengths are 1.78 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Mo(1) atoms. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Cs(2), three equivalent Cs(1), and one Mo(1) atom. Br(1) is bonded to two equivalent Cs(1) and three equivalent Cs(2) atoms to form corner-sharing BrCs5 trigonal bipyramids.