Ba3La2Cl12 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 Cl(2) atoms. In the second Ba site, Ba(2) is bonded to two equivalent Cl(1), two equivalent Cl(3), and eight equivalent Cl(2) atoms to form BaCl12 cuboctahedra that share corners with two equivalent Ba(2)Cl12 cuboctahedra, edges with five equivalent Ba(2)Cl12 cuboctahedra, edges with four equivalent La(1)Cl7 pentagonal bipyramids, and faces with two equivalent La(1)Cl7 pentagonal bipyramids. La(1) is bonded to one Cl(3), two equivalent Cl(1), and four equivalent Cl(2) atoms to form distorted LaCl7 pentagonal bipyramids that share edges with four equivalent Ba(2)Cl12 cuboctahedra,  an edgeedge with one La(1)Cl7 pentagonal bipyramid, and faces with two equivalent Ba(2)Cl12 cuboctahedra. There are three inequivalent Cl sites. In the first Cl site, Cl(1) is bonded to two equivalent Ba(2) and two equivalent La(1) atoms to form ClBa2La2 tetrahedra that share corners with sixteen equivalent Cl(2)Ba3La tetrahedra, edges with two equivalent Cl(1)Ba2La2 tetrahedra, and edges with four equivalent Cl(2)Ba3La tetrahedra. In the second Cl site, Cl(2) is bonded to one Ba(1), two equivalent Ba(2), and one La(1) atom to form distorted ClBa3La tetrahedra that share corners with four equivalent Cl(1)Ba2La2 tetrahedra, corners with fourteen equivalent Cl(2)Ba3La tetrahedra,  an edgeedge with one Cl(1)Ba2La2 tetrahedra, and edges with five equivalent Cl(2)Ba3La tetrahedra. In the third Cl site, Cl(3) is bonded in a distorted T-shaped geometry to two equivalent Ba(2) and one La(1) atom.
Ba3La2Cl12 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 Cl(2) atoms. All Ba(1)-Cl(2) bond lengths are 3.20 Å. In the second Ba site, Ba(2) is bonded to two equivalent Cl(1), two equivalent Cl(3), and eight equivalent Cl(2) atoms to form BaCl12 cuboctahedra that share corners with two equivalent Ba(2)Cl12 cuboctahedra, edges with five equivalent Ba(2)Cl12 cuboctahedra, edges with four equivalent La(1)Cl7 pentagonal bipyramids, and faces with two equivalent La(1)Cl7 pentagonal bipyramids. Both Ba(2)-Cl(1) bond lengths are 3.50 Å. Both Ba(2)-Cl(3) bond lengths are 3.58 Å. There are four shorter (3.44 Å) and four longer (3.55 Å) Ba(2)-Cl(2) bond lengths. La(1) is bonded to one Cl(3), two equivalent Cl(1), and four equivalent Cl(2) atoms to form distorted LaCl7 pentagonal bipyramids that share edges with four equivalent Ba(2)Cl12 cuboctahedra,  an edgeedge with one La(1)Cl7 pentagonal bipyramid, and faces with two equivalent Ba(2)Cl12 cuboctahedra. The La(1)-Cl(3) bond length is 2.91 Å. Both La(1)-Cl(1) bond lengths are 2.91 Å. All La(1)-Cl(2) bond lengths are 2.81 Å. There are three inequivalent Cl sites. In the first Cl site, Cl(1) is bonded to two equivalent Ba(2) and two equivalent La(1) atoms to form ClBa2La2 tetrahedra that share corners with sixteen equivalent Cl(2)Ba3La tetrahedra, edges with two equivalent Cl(1)Ba2La2 tetrahedra, and edges with four equivalent Cl(2)Ba3La tetrahedra. In the second Cl site, Cl(2) is bonded to one Ba(1), two equivalent Ba(2), and one La(1) atom to form distorted ClBa3La tetrahedra that share corners with four equivalent Cl(1)Ba2La2 tetrahedra, corners with fourteen equivalent Cl(2)Ba3La tetrahedra,  an edgeedge with one Cl(1)Ba2La2 tetrahedra, and edges with five equivalent Cl(2)Ba3La tetrahedra. In the third Cl site, Cl(3) is bonded in a distorted T-shaped geometry to two equivalent Ba(2) and one La(1) atom.