La4Al5Br2 crystallizes in the orthorhombic Cmmm space group. There are three inequivalent La sites. In the first La site, La(1) is bonded in a 10-coordinate geometry to two equivalent Al(1), two equivalent Al(3), four equivalent Al(2), and two equivalent Br(1) atoms. In the second La site, La(2) is bonded in a 3-coordinate geometry to two equivalent Al(2), four equivalent Al(3), one Br(1), and two equivalent Br(2) atoms. In the third La site, La(3) is bonded in a 1-coordinate geometry to two equivalent Al(3), four equivalent Al(1), four equivalent Al(2), and one Br(2) atom. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded in a 9-coordinate geometry to two equivalent La(1), four equivalent La(3), one Al(1), and two equivalent Al(2) atoms. In the second Al site, Al(2) is bonded in a 9-coordinate geometry to two equivalent La(1), two equivalent La(2), two equivalent La(3), one Al(1), and two equivalent Al(3) atoms. In the third Al site, Al(3) is bonded in a 9-coordinate geometry to one La(1), one La(3), four equivalent La(2), one Al(3), and two equivalent Al(2) atoms. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded in a rectangular see-saw-like geometry to two equivalent La(1) and two equivalent La(2) atoms. In the second Br site, Br(2) is bonded to one La(3) and four equivalent La(2) atoms to form edge-sharing BrLa5 square pyramids.
La4Al5Br2 crystallizes in the orthorhombic Cmmm space group. There are three inequivalent La sites. In the first La site, La(1) is bonded in a 10-coordinate geometry to two equivalent Al(1), two equivalent Al(3), four equivalent Al(2), and two equivalent Br(1) atoms. Both La(1)-Al(1) bond lengths are 3.34 Å. Both La(1)-Al(3) bond lengths are 3.21 Å. All La(1)-Al(2) bond lengths are 3.43 Å. Both La(1)-Br(1) bond lengths are 3.18 Å. In the second La site, La(2) is bonded in a 3-coordinate geometry to two equivalent Al(2), four equivalent Al(3), one Br(1), and two equivalent Br(2) atoms. There is one shorter (3.23 Å) and one longer (3.46 Å) La(2)-Al(2) bond length. There are two shorter (3.21 Å) and two longer (3.38 Å) La(2)-Al(3) bond lengths. The La(2)-Br(1) bond length is 3.16 Å. Both La(2)-Br(2) bond lengths are 3.18 Å. In the third La site, La(3) is bonded in a 1-coordinate geometry to two equivalent Al(3), four equivalent Al(1), four equivalent Al(2), and one Br(2) atom. Both La(3)-Al(3) bond lengths are 3.57 Å. All La(3)-Al(1) bond lengths are 3.45 Å. All La(3)-Al(2) bond lengths are 3.30 Å. The La(3)-Br(2) bond length is 3.32 Å. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded in a 9-coordinate geometry to two equivalent La(1), four equivalent La(3), one Al(1), and two equivalent Al(2) atoms. The Al(1)-Al(1) bond length is 2.58 Å. Both Al(1)-Al(2) bond lengths are 2.57 Å. In the second Al site, Al(2) is bonded in a 9-coordinate geometry to two equivalent La(1), two equivalent La(2), two equivalent La(3), one Al(1), and two equivalent Al(3) atoms. Both Al(2)-Al(3) bond lengths are 2.56 Å. In the third Al site, Al(3) is bonded in a 9-coordinate geometry to one La(1), one La(3), four equivalent La(2), one Al(3), and two equivalent Al(2) atoms. The Al(3)-Al(3) bond length is 2.56 Å. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded in a rectangular see-saw-like geometry to two equivalent La(1) and two equivalent La(2) atoms. In the second Br site, Br(2) is bonded to one La(3) and four equivalent La(2) atoms to form edge-sharing BrLa5 square pyramids.