Ba3Bi2O5I2 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 4-coordinate geometry to four equivalent O(1) and five equivalent I(1) atoms. In the second Ba site, Ba(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(2)O12 cuboctahedra, faces with four equivalent Ba(2)O12 cuboctahedra, and faces with eight equivalent Bi(1)IO5 square pyramids. Bi(1) is bonded to one O(2), four equivalent O(1), and one I(1) atom to form BiIO5 square pyramids that share corners with five equivalent Bi(1)IO5 square pyramids and faces with four equivalent Ba(2)O12 cuboctahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Bi(1) atoms to form a mixture of distorted corner, edge, and face-sharing OBa4Bi2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Ba(2) and two equivalent Bi(1) atoms. I(1) is bonded in a distorted hexagonal planar geometry to five equivalent Ba(1) and one Bi(1) atom.
Ba3Bi2O5I2 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 4-coordinate geometry to four equivalent O(1) and five equivalent I(1) atoms. All Ba(1)-O(1) bond lengths are 2.88 Å. There are four shorter (3.69 Å) and one longer (4.09 Å) Ba(1)-I(1) bond length. In the second Ba site, Ba(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(2)O12 cuboctahedra, faces with four equivalent Ba(2)O12 cuboctahedra, and faces with eight equivalent Bi(1)IO5 square pyramids. All Ba(2)-O(2) bond lengths are 3.29 Å. All Ba(2)-O(1) bond lengths are 3.28 Å. Bi(1) is bonded to one O(2), four equivalent O(1), and one I(1) atom to form BiIO5 square pyramids that share corners with five equivalent Bi(1)IO5 square pyramids and faces with four equivalent Ba(2)O12 cuboctahedra. The Bi(1)-O(2) bond length is 2.18 Å. All Bi(1)-O(1) bond lengths are 2.33 Å. The Bi(1)-I(1) bond length is 3.50 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Bi(1) atoms to form a mixture of distorted corner, edge, and face-sharing OBa4Bi2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Ba(2) and two equivalent Bi(1) atoms. I(1) is bonded in a distorted hexagonal planar geometry to five equivalent Ba(1) and one Bi(1) atom.