K3B6O10Br crystallizes in the trigonal R3m space group. K(1) is bonded to two equivalent O(1), four equivalent O(3), and two equivalent Br(1) atoms to form distorted KBr2O6 hexagonal bipyramids that share corners with four equivalent K(1)Br2O6 hexagonal bipyramids, corners with four equivalent B(1)O4 tetrahedra, edges with six equivalent K(1)Br2O6 hexagonal bipyramids, and  an edgeedge with one B(1)O4 tetrahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form BO4 tetrahedra that share corners with four equivalent K(1)Br2O6 hexagonal bipyramids, corners with two equivalent B(1)O4 tetrahedra, and  an edgeedge with one K(1)Br2O6 hexagonal bipyramid. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1), one B(1), and one B(2) atom. In the second O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1), one B(1), and one B(2) atom. In the third O site, O(2) is bonded in a trigonal planar geometry to three equivalent B(1) atoms. Br(1) is bonded to six equivalent K(1) atoms to form corner-sharing BrK6 octahedra. The corner-sharing octahedral tilt angles are 18°.
K3B6O10Br crystallizes in the trigonal R3m space group. K(1) is bonded to two equivalent O(1), four equivalent O(3), and two equivalent Br(1) atoms to form distorted KBr2O6 hexagonal bipyramids that share corners with four equivalent K(1)Br2O6 hexagonal bipyramids, corners with four equivalent B(1)O4 tetrahedra, edges with six equivalent K(1)Br2O6 hexagonal bipyramids, and  an edgeedge with one B(1)O4 tetrahedra. Both K(1)-O(1) bond lengths are 2.91 Å. There are two shorter (2.83 Å) and two longer (2.84 Å) K(1)-O(3) bond lengths. There is one shorter (3.34 Å) and one longer (3.36 Å) K(1)-Br(1) bond length. There are two inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form BO4 tetrahedra that share corners with four equivalent K(1)Br2O6 hexagonal bipyramids, corners with two equivalent B(1)O4 tetrahedra, and  an edgeedge with one K(1)Br2O6 hexagonal bipyramid. The B(1)-O(1) bond length is 1.46 Å. The B(1)-O(2) bond length is 1.55 Å. Both B(1)-O(3) bond lengths are 1.47 Å. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(3) atoms. The B(2)-O(1) bond length is 1.38 Å. Both B(2)-O(3) bond lengths are 1.37 Å. There are three inequivalent O sites. In the first O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1), one B(1), and one B(2) atom. In the second O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1), one B(1), and one B(2) atom. In the third O site, O(2) is bonded in a trigonal planar geometry to three equivalent B(1) atoms. Br(1) is bonded to six equivalent K(1) atoms to form corner-sharing BrK6 octahedra. The corner-sharing octahedral tilt angles are 18°.