Ba4Cu2O4IBr crystallizes in the monoclinic P2/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted trigonal non-coplanar geometry to one O(2), two equivalent O(1), one I(1), and two equivalent Br(1) atoms. In the second Ba site, Ba(2) is bonded in a distorted trigonal non-coplanar geometry to one O(1), two equivalent O(2), two equivalent I(1), and one Br(1) atom. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a linear geometry to two equivalent O(1) atoms. In the second Cu site, Cu(2) is bonded in a linear geometry to two equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Ba(2), two equivalent Ba(1), and one Cu(1) atom to form OBa3Cu tetrahedra that share corners with three equivalent Br(1)Ba6 octahedra, corners with three equivalent O(1)Ba3Cu tetrahedra, corners with four equivalent O(2)Ba3Cu tetrahedra,  an edgeedge with one Br(1)Ba6 octahedra, and edges with two equivalent I(1)Ba6 octahedra. The corner-sharing octahedral tilt angles range from 30-31°. In the second O site, O(2) is bonded to one Ba(1), two equivalent Ba(2), and one Cu(2) atom to form OBa3Cu tetrahedra that share corners with three equivalent I(1)Ba6 octahedra, corners with three equivalent O(2)Ba3Cu tetrahedra, corners with four equivalent O(1)Ba3Cu tetrahedra,  an edgeedge with one I(1)Ba6 octahedra, and edges with two equivalent Br(1)Ba6 octahedra. The corner-sharing octahedral tilt angles range from 29-31°. I(1) is bonded to two equivalent Ba(1) and four equivalent Ba(2) atoms to form distorted IBa6 octahedra that share corners with six equivalent O(2)Ba3Cu tetrahedra, edges with two equivalent I(1)Ba6 octahedra, edges with four equivalent Br(1)Ba6 octahedra, edges with two equivalent O(2)Ba3Cu tetrahedra, and edges with four equivalent O(1)Ba3Cu tetrahedra. Br(1) is bonded to two equivalent Ba(2) and four equivalent Ba(1) atoms to form distorted BrBa6 octahedra that share corners with six equivalent O(1)Ba3Cu tetrahedra, edges with two equivalent Br(1)Ba6 octahedra, edges with four equivalent I(1)Ba6 octahedra, edges with two equivalent O(1)Ba3Cu tetrahedra, and edges with four equivalent O(2)Ba3Cu tetrahedra.
Ba4Cu2O4IBr crystallizes in the monoclinic P2/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted trigonal non-coplanar geometry to one O(2), two equivalent O(1), one I(1), and two equivalent Br(1) atoms. The Ba(1)-O(2) bond length is 2.61 Å. Both Ba(1)-O(1) bond lengths are 2.63 Å. The Ba(1)-I(1) bond length is 3.60 Å. Both Ba(1)-Br(1) bond lengths are 3.58 Å. In the second Ba site, Ba(2) is bonded in a distorted trigonal non-coplanar geometry to one O(1), two equivalent O(2), two equivalent I(1), and one Br(1) atom. The Ba(2)-O(1) bond length is 2.63 Å. Both Ba(2)-O(2) bond lengths are 2.61 Å. Both Ba(2)-I(1) bond lengths are 3.62 Å. The Ba(2)-Br(1) bond length is 3.61 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a linear geometry to two equivalent O(1) atoms. Both Cu(1)-O(1) bond lengths are 1.81 Å. In the second Cu site, Cu(2) is bonded in a linear geometry to two equivalent O(2) atoms. Both Cu(2)-O(2) bond lengths are 1.81 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Ba(2), two equivalent Ba(1), and one Cu(1) atom to form OBa3Cu tetrahedra that share corners with three equivalent Br(1)Ba6 octahedra, corners with three equivalent O(1)Ba3Cu tetrahedra, corners with four equivalent O(2)Ba3Cu tetrahedra,  an edgeedge with one Br(1)Ba6 octahedra, and edges with two equivalent I(1)Ba6 octahedra. The corner-sharing octahedral tilt angles range from 30-31°. In the second O site, O(2) is bonded to one Ba(1), two equivalent Ba(2), and one Cu(2) atom to form OBa3Cu tetrahedra that share corners with three equivalent I(1)Ba6 octahedra, corners with three equivalent O(2)Ba3Cu tetrahedra, corners with four equivalent O(1)Ba3Cu tetrahedra,  an edgeedge with one I(1)Ba6 octahedra, and edges with two equivalent Br(1)Ba6 octahedra. The corner-sharing octahedral tilt angles range from 29-31°. I(1) is bonded to two equivalent Ba(1) and four equivalent Ba(2) atoms to form distorted IBa6 octahedra that share corners with six equivalent O(2)Ba3Cu tetrahedra, edges with two equivalent I(1)Ba6 octahedra, edges with four equivalent Br(1)Ba6 octahedra, edges with two equivalent O(2)Ba3Cu tetrahedra, and edges with four equivalent O(1)Ba3Cu tetrahedra. Br(1) is bonded to two equivalent Ba(2) and four equivalent Ba(1) atoms to form distorted BrBa6 octahedra that share corners with six equivalent O(1)Ba3Cu tetrahedra, edges with two equivalent Br(1)Ba6 octahedra, edges with four equivalent I(1)Ba6 octahedra, edges with two equivalent O(1)Ba3Cu tetrahedra, and edges with four equivalent O(2)Ba3Cu tetrahedra.