Ba2Co4BrO7 crystallizes in the monoclinic C2 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one O(5), one O(6), one O(7), two equivalent O(1), two equivalent O(2), two equivalent O(3), and one Br(1) atom. In the second Ba site, Ba(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), and four equivalent Br(1) atoms. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(5), one O(6), two equivalent O(4), and two equivalent O(7) atoms to form CoO6 octahedra that share corners with two equivalent Co(3)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(4)O6 octahedra, and edges with two equivalent Co(5)O6 octahedra. In the second Co site, Co(2) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form CoO6 octahedra that share corners with two equivalent Co(3)O4 tetrahedra, edges with two equivalent Co(4)O6 octahedra, edges with two equivalent Co(5)O6 octahedra, and edges with four equivalent Co(1)O6 octahedra. In the third Co site, Co(3) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CoO4 tetrahedra. The corner-sharing octahedral tilt angles range from 53-57°. In the fourth Co site, Co(4) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form CoO6 octahedra that share corners with three equivalent Co(5)O6 octahedra, corners with three equivalent Co(3)O4 tetrahedra,  an edgeedge with one Co(2)O6 octahedra, and edges with two equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. In the fifth Co site, Co(5) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms to form a mixture of edge and corner-sharing CoO6 octahedra. The corner-sharing octahedral tilt angles are 7°. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Co(2), one Co(3), and two equivalent Co(1) atoms. In the second O site, O(5) is bonded to one Ba(1), one Co(1), one Co(2), one Co(4), and one Co(5) atom to form distorted OBaCo4 trigonal bipyramids that share  a cornercorner with one Br(1)Ba5 trigonal bipyramid, corners with three equivalent O(6)BaCo4 trigonal bipyramids,  an edgeedge with one O(5)BaCo4 trigonal bipyramid, edges with two equivalent O(6)BaCo4 trigonal bipyramids, and edges with three equivalent O(7)BaCo4 trigonal bipyramids. In the third O site, O(6) is bonded to one Ba(1), one Co(1), one Co(2), one Co(4), and one Co(5) atom to form distorted OBaCo4 trigonal bipyramids that share  a cornercorner with one Br(1)Ba5 trigonal bipyramid, corners with three equivalent O(5)BaCo4 trigonal bipyramids,  an edgeedge with one O(6)BaCo4 trigonal bipyramid, edges with two equivalent O(5)BaCo4 trigonal bipyramids, and edges with three equivalent O(7)BaCo4 trigonal bipyramids. In the fourth O site, O(7) is bonded to one Ba(1), one Co(4), one Co(5), and two equivalent Co(1) atoms to form distorted OBaCo4 trigonal bipyramids that share  a cornercorner with one Br(1)Ba5 trigonal bipyramid, corners with three equivalent O(7)BaCo4 trigonal bipyramids, edges with three equivalent O(5)BaCo4 trigonal bipyramids, and edges with three equivalent O(6)BaCo4 trigonal bipyramids. In the fifth O site, O(1) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Co(3), and one Co(4) atom. In the sixth O site, O(2) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Co(3), and one Co(4) atom. In the seventh O site, O(3) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Co(3), and one Co(4) atom. Br(1) is bonded to one Ba(1) and four equivalent Ba(2) atoms to form distorted BrBa5 trigonal bipyramids that share  a cornercorner with one O(5)BaCo4 trigonal bipyramid,  a cornercorner with one O(6)BaCo4 trigonal bipyramid,  a cornercorner with one O(7)BaCo4 trigonal bipyramid, corners with six equivalent Br(1)Ba5 trigonal bipyramids, and edges with three equivalent Br(1)Ba5 trigonal bipyramids.
Ba2Co4BrO7 crystallizes in the monoclinic C2 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one O(5), one O(6), one O(7), two equivalent O(1), two equivalent O(2), two equivalent O(3), and one Br(1) atom. The Ba(1)-O(5) bond length is 2.76 Å. The Ba(1)-O(6) bond length is 2.77 Å. The Ba(1)-O(7) bond length is 2.77 Å. There is one shorter (3.00 Å) and one longer (3.05 Å) Ba(1)-O(1) bond length. There is one shorter (2.99 Å) and one longer (3.05 Å) Ba(1)-O(2) bond length. There is one shorter (3.03 Å) and one longer (3.04 Å) Ba(1)-O(3) bond length. The Ba(1)-Br(1) bond length is 3.41 Å. In the second Ba site, Ba(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), and four equivalent Br(1) atoms. The Ba(2)-O(1) bond length is 2.62 Å. The Ba(2)-O(2) bond length is 2.63 Å. The Ba(2)-O(3) bond length is 2.59 Å. There are a spread of Ba(2)-Br(1) bond distances ranging from 3.50-3.76 Å. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(5), one O(6), two equivalent O(4), and two equivalent O(7) atoms to form CoO6 octahedra that share corners with two equivalent Co(3)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(4)O6 octahedra, and edges with two equivalent Co(5)O6 octahedra. The Co(1)-O(5) bond length is 2.02 Å. The Co(1)-O(6) bond length is 2.02 Å. Both Co(1)-O(4) bond lengths are 2.06 Å. Both Co(1)-O(7) bond lengths are 2.02 Å. In the second Co site, Co(2) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form CoO6 octahedra that share corners with two equivalent Co(3)O4 tetrahedra, edges with two equivalent Co(4)O6 octahedra, edges with two equivalent Co(5)O6 octahedra, and edges with four equivalent Co(1)O6 octahedra. Both Co(2)-O(4) bond lengths are 2.07 Å. Both Co(2)-O(5) bond lengths are 2.03 Å. Both Co(2)-O(6) bond lengths are 2.03 Å. In the third Co site, Co(3) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CoO4 tetrahedra. The corner-sharing octahedral tilt angles range from 53-57°. The Co(3)-O(1) bond length is 1.85 Å. The Co(3)-O(2) bond length is 1.85 Å. The Co(3)-O(3) bond length is 1.91 Å. The Co(3)-O(4) bond length is 1.94 Å. In the fourth Co site, Co(4) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form CoO6 octahedra that share corners with three equivalent Co(5)O6 octahedra, corners with three equivalent Co(3)O4 tetrahedra,  an edgeedge with one Co(2)O6 octahedra, and edges with two equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. The Co(4)-O(1) bond length is 2.09 Å. The Co(4)-O(2) bond length is 2.09 Å. The Co(4)-O(3) bond length is 2.05 Å. The Co(4)-O(5) bond length is 2.09 Å. The Co(4)-O(6) bond length is 2.09 Å. The Co(4)-O(7) bond length is 2.13 Å. In the fifth Co site, Co(5) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms to form a mixture of edge and corner-sharing CoO6 octahedra. The corner-sharing octahedral tilt angles are 7°. Both Co(5)-O(5) bond lengths are 2.13 Å. Both Co(5)-O(6) bond lengths are 2.13 Å. Both Co(5)-O(7) bond lengths are 2.11 Å. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Co(2), one Co(3), and two equivalent Co(1) atoms. In the second O site, O(5) is bonded to one Ba(1), one Co(1), one Co(2), one Co(4), and one Co(5) atom to form distorted OBaCo4 trigonal bipyramids that share  a cornercorner with one Br(1)Ba5 trigonal bipyramid, corners with three equivalent O(6)BaCo4 trigonal bipyramids,  an edgeedge with one O(5)BaCo4 trigonal bipyramid, edges with two equivalent O(6)BaCo4 trigonal bipyramids, and edges with three equivalent O(7)BaCo4 trigonal bipyramids. In the third O site, O(6) is bonded to one Ba(1), one Co(1), one Co(2), one Co(4), and one Co(5) atom to form distorted OBaCo4 trigonal bipyramids that share  a cornercorner with one Br(1)Ba5 trigonal bipyramid, corners with three equivalent O(5)BaCo4 trigonal bipyramids,  an edgeedge with one O(6)BaCo4 trigonal bipyramid, edges with two equivalent O(5)BaCo4 trigonal bipyramids, and edges with three equivalent O(7)BaCo4 trigonal bipyramids. In the fourth O site, O(7) is bonded to one Ba(1), one Co(4), one Co(5), and two equivalent Co(1) atoms to form distorted OBaCo4 trigonal bipyramids that share  a cornercorner with one Br(1)Ba5 trigonal bipyramid, corners with three equivalent O(7)BaCo4 trigonal bipyramids, edges with three equivalent O(5)BaCo4 trigonal bipyramids, and edges with three equivalent O(6)BaCo4 trigonal bipyramids. In the fifth O site, O(1) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Co(3), and one Co(4) atom. In the sixth O site, O(2) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Co(3), and one Co(4) atom. In the seventh O site, O(3) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Co(3), and one Co(4) atom. Br(1) is bonded to one Ba(1) and four equivalent Ba(2) atoms to form distorted BrBa5 trigonal bipyramids that share  a cornercorner with one O(5)BaCo4 trigonal bipyramid,  a cornercorner with one O(6)BaCo4 trigonal bipyramid,  a cornercorner with one O(7)BaCo4 trigonal bipyramid, corners with six equivalent Br(1)Ba5 trigonal bipyramids, and edges with three equivalent Br(1)Ba5 trigonal bipyramids.