Ba2Sb2O7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms to form BaO8 hexagonal bipyramids that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with two equivalent Sb(2)O6 octahedra, edges with four equivalent Ba(2)O8 hexagonal bipyramids, edges with two equivalent Sb(2)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. In the second Ba site, Ba(2) is bonded to four equivalent O(1) and four equivalent O(3) atoms to form distorted BaO8 hexagonal bipyramids that share edges with two equivalent Ba(2)O8 hexagonal bipyramids, edges with four equivalent Ba(1)O8 hexagonal bipyramids, edges with two equivalent Sb(1)O6 octahedra, and edges with four equivalent Sb(2)O6 octahedra. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form SbO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, corners with four equivalent Sb(2)O6 octahedra, edges with two equivalent Ba(2)O8 hexagonal bipyramids, and edges with four equivalent Ba(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 40-43°. In the second Sb site, Sb(2) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form SbO6 octahedra that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with four equivalent Sb(1)O6 octahedra, edges with two equivalent Ba(1)O8 hexagonal bipyramids, and edges with four equivalent Ba(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 40°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Sb(1), and one Sb(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(1) and two equivalent Sb(1) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ba(1), two equivalent Ba(2), and one Sb(2) atom.
Ba2Sb2O7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms to form BaO8 hexagonal bipyramids that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with two equivalent Sb(2)O6 octahedra, edges with four equivalent Ba(2)O8 hexagonal bipyramids, edges with two equivalent Sb(2)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. Both Ba(1)-O(2) bond lengths are 2.96 Å. Both Ba(1)-O(3) bond lengths are 2.55 Å. All Ba(1)-O(1) bond lengths are 2.75 Å. In the second Ba site, Ba(2) is bonded to four equivalent O(1) and four equivalent O(3) atoms to form distorted BaO8 hexagonal bipyramids that share edges with two equivalent Ba(2)O8 hexagonal bipyramids, edges with four equivalent Ba(1)O8 hexagonal bipyramids, edges with two equivalent Sb(1)O6 octahedra, and edges with four equivalent Sb(2)O6 octahedra. All Ba(2)-O(1) bond lengths are 3.00 Å. All Ba(2)-O(3) bond lengths are 2.64 Å. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form SbO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, corners with four equivalent Sb(2)O6 octahedra, edges with two equivalent Ba(2)O8 hexagonal bipyramids, and edges with four equivalent Ba(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 40-43°. Both Sb(1)-O(2) bond lengths are 2.10 Å. All Sb(1)-O(1) bond lengths are 2.03 Å. In the second Sb site, Sb(2) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form SbO6 octahedra that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with four equivalent Sb(1)O6 octahedra, edges with two equivalent Ba(1)O8 hexagonal bipyramids, and edges with four equivalent Ba(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 40°. Both Sb(2)-O(3) bond lengths are 1.93 Å. All Sb(2)-O(1) bond lengths are 2.10 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Sb(1), and one Sb(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(1) and two equivalent Sb(1) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ba(1), two equivalent Ba(2), and one Sb(2) atom.