Ba3La2Br12 crystallizes in the tetragonal P4/mbm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a body-centered cubic geometry to eight equivalent Br(2) atoms. In the second Ba site, Ba(2) is bonded to two equivalent Br(1), two equivalent Br(3), and eight equivalent Br(2) atoms to form BaBr12 cuboctahedra that share corners with two equivalent Ba(2)Br12 cuboctahedra, edges with five equivalent Ba(2)Br12 cuboctahedra, edges with four equivalent La(1)Br7 pentagonal bipyramids, and faces with two equivalent La(1)Br7 pentagonal bipyramids. La(1) is bonded to one Br(3), two equivalent Br(1), and four equivalent Br(2) atoms to form distorted LaBr7 pentagonal bipyramids that share edges with four equivalent Ba(2)Br12 cuboctahedra,  an edgeedge with one La(1)Br7 pentagonal bipyramid, and faces with two equivalent Ba(2)Br12 cuboctahedra. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded to two equivalent Ba(2) and two equivalent La(1) atoms to form BrBa2La2 tetrahedra that share corners with sixteen equivalent Br(2)Ba3La tetrahedra, edges with two equivalent Br(1)Ba2La2 tetrahedra, and edges with four equivalent Br(2)Ba3La tetrahedra. In the second Br site, Br(2) is bonded to one Ba(1), two equivalent Ba(2), and one La(1) atom to form distorted BrBa3La tetrahedra that share corners with four equivalent Br(1)Ba2La2 tetrahedra, corners with fourteen equivalent Br(2)Ba3La tetrahedra,  an edgeedge with one Br(1)Ba2La2 tetrahedra, and edges with five equivalent Br(2)Ba3La tetrahedra. In the third Br site, Br(3) is bonded in a distorted T-shaped geometry to two equivalent Ba(2) and one La(1) atom.
Ba3La2Br12 crystallizes in the tetragonal P4/mbm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a body-centered cubic geometry to eight equivalent Br(2) atoms. All Ba(1)-Br(2) bond lengths are 3.37 Å. In the second Ba site, Ba(2) is bonded to two equivalent Br(1), two equivalent Br(3), and eight equivalent Br(2) atoms to form BaBr12 cuboctahedra that share corners with two equivalent Ba(2)Br12 cuboctahedra, edges with five equivalent Ba(2)Br12 cuboctahedra, edges with four equivalent La(1)Br7 pentagonal bipyramids, and faces with two equivalent La(1)Br7 pentagonal bipyramids. Both Ba(2)-Br(1) bond lengths are 3.70 Å. Both Ba(2)-Br(3) bond lengths are 3.78 Å. There are four shorter (3.69 Å) and four longer (3.70 Å) Ba(2)-Br(2) bond lengths. La(1) is bonded to one Br(3), two equivalent Br(1), and four equivalent Br(2) atoms to form distorted LaBr7 pentagonal bipyramids that share edges with four equivalent Ba(2)Br12 cuboctahedra,  an edgeedge with one La(1)Br7 pentagonal bipyramid, and faces with two equivalent Ba(2)Br12 cuboctahedra. The La(1)-Br(3) bond length is 3.02 Å. Both La(1)-Br(1) bond lengths are 3.08 Å. All La(1)-Br(2) bond lengths are 2.98 Å. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded to two equivalent Ba(2) and two equivalent La(1) atoms to form BrBa2La2 tetrahedra that share corners with sixteen equivalent Br(2)Ba3La tetrahedra, edges with two equivalent Br(1)Ba2La2 tetrahedra, and edges with four equivalent Br(2)Ba3La tetrahedra. In the second Br site, Br(2) is bonded to one Ba(1), two equivalent Ba(2), and one La(1) atom to form distorted BrBa3La tetrahedra that share corners with four equivalent Br(1)Ba2La2 tetrahedra, corners with fourteen equivalent Br(2)Ba3La tetrahedra,  an edgeedge with one Br(1)Ba2La2 tetrahedra, and edges with five equivalent Br(2)Ba3La tetrahedra. In the third Br site, Br(3) is bonded in a distorted T-shaped geometry to two equivalent Ba(2) and one La(1) atom.