La4Cu5As8 crystallizes in the orthorhombic Amm2 space group. There are four inequivalent La sites. In the first La site, La(1) is bonded to four equivalent Cu(1), two equivalent As(3), two equivalent As(4), and four equivalent As(5) atoms to form distorted LaCu4As8 cuboctahedra that share corners with four equivalent La(1)Cu4As8 cuboctahedra, corners with eight equivalent Cu(1)La4As4 tetrahedra, edges with four equivalent Cu(1)La4As4 tetrahedra, and faces with four equivalent La(2)Cu4As8 cuboctahedra. In the second La site, La(2) is bonded to four equivalent Cu(1), two equivalent As(3), two equivalent As(4), and four equivalent As(5) atoms to form distorted LaCu4As8 cuboctahedra that share corners with four equivalent La(2)Cu4As8 cuboctahedra, corners with eight equivalent Cu(1)La4As4 tetrahedra, edges with four equivalent Cu(1)La4As4 tetrahedra, and faces with four equivalent La(1)Cu4As8 cuboctahedra. In the third La site, La(3) is bonded in a 14-coordinate geometry to two equivalent Cu(2), four equivalent Cu(1), two equivalent As(1), two equivalent As(2), and four equivalent As(5) atoms. In the fourth La site, La(4) is bonded in a 14-coordinate geometry to two equivalent Cu(2), four equivalent Cu(1), two equivalent As(1), two equivalent As(2), and four equivalent As(5) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one La(1), one La(2), one La(3), one La(4), one As(1), one As(2), one As(3), and one As(4) atom to form distorted CuLa4As4 tetrahedra that share corners with two equivalent La(1)Cu4As8 cuboctahedra, corners with two equivalent La(2)Cu4As8 cuboctahedra,  an edgeedge with one La(1)Cu4As8 cuboctahedra,  an edgeedge with one La(2)Cu4As8 cuboctahedra, edges with four equivalent Cu(1)La4As4 tetrahedra, and faces with four equivalent Cu(1)La4As4 tetrahedra. In the second Cu site, Cu(2) is bonded in a 9-coordinate geometry to two equivalent La(3), two equivalent La(4), one As(2), and four equivalent As(5) atoms. There are five inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to two equivalent La(3), two equivalent La(4), and four equivalent Cu(1) atoms. In the second As site, As(2) is bonded in a 9-coordinate geometry to two equivalent La(3), two equivalent La(4), one Cu(2), and four equivalent Cu(1) atoms. In the third As site, As(3) is bonded in a 8-coordinate geometry to two equivalent La(1), two equivalent La(2), and four equivalent Cu(1) atoms. In the fourth As site, As(4) is bonded in a 8-coordinate geometry to two equivalent La(1), two equivalent La(2), and four equivalent Cu(1) atoms. In the fifth As site, As(5) is bonded in a 7-coordinate geometry to one La(1), one La(2), one La(3), one La(4), one Cu(2), and two equivalent As(5) atoms.
La4Cu5As8 crystallizes in the orthorhombic Amm2 space group. There are four inequivalent La sites. In the first La site, La(1) is bonded to four equivalent Cu(1), two equivalent As(3), two equivalent As(4), and four equivalent As(5) atoms to form distorted LaCu4As8 cuboctahedra that share corners with four equivalent La(1)Cu4As8 cuboctahedra, corners with eight equivalent Cu(1)La4As4 tetrahedra, edges with four equivalent Cu(1)La4As4 tetrahedra, and faces with four equivalent La(2)Cu4As8 cuboctahedra. All La(1)-Cu(1) bond lengths are 3.31 Å. Both La(1)-As(3) bond lengths are 3.15 Å. Both La(1)-As(4) bond lengths are 3.12 Å. All La(1)-As(5) bond lengths are 3.22 Å. In the second La site, La(2) is bonded to four equivalent Cu(1), two equivalent As(3), two equivalent As(4), and four equivalent As(5) atoms to form distorted LaCu4As8 cuboctahedra that share corners with four equivalent La(2)Cu4As8 cuboctahedra, corners with eight equivalent Cu(1)La4As4 tetrahedra, edges with four equivalent Cu(1)La4As4 tetrahedra, and faces with four equivalent La(1)Cu4As8 cuboctahedra. All La(2)-Cu(1) bond lengths are 3.33 Å. Both La(2)-As(3) bond lengths are 3.10 Å. Both La(2)-As(4) bond lengths are 3.14 Å. All La(2)-As(5) bond lengths are 3.18 Å. In the third La site, La(3) is bonded in a 14-coordinate geometry to two equivalent Cu(2), four equivalent Cu(1), two equivalent As(1), two equivalent As(2), and four equivalent As(5) atoms. Both La(3)-Cu(2) bond lengths are 3.17 Å. All La(3)-Cu(1) bond lengths are 3.29 Å. Both La(3)-As(1) bond lengths are 3.12 Å. Both La(3)-As(2) bond lengths are 3.10 Å. All La(3)-As(5) bond lengths are 3.22 Å. In the fourth La site, La(4) is bonded in a 14-coordinate geometry to two equivalent Cu(2), four equivalent Cu(1), two equivalent As(1), two equivalent As(2), and four equivalent As(5) atoms. Both La(4)-Cu(2) bond lengths are 3.18 Å. All La(4)-Cu(1) bond lengths are 3.32 Å. Both La(4)-As(1) bond lengths are 3.09 Å. Both La(4)-As(2) bond lengths are 3.16 Å. All La(4)-As(5) bond lengths are 3.24 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one La(1), one La(2), one La(3), one La(4), one As(1), one As(2), one As(3), and one As(4) atom to form distorted CuLa4As4 tetrahedra that share corners with two equivalent La(1)Cu4As8 cuboctahedra, corners with two equivalent La(2)Cu4As8 cuboctahedra,  an edgeedge with one La(1)Cu4As8 cuboctahedra,  an edgeedge with one La(2)Cu4As8 cuboctahedra, edges with four equivalent Cu(1)La4As4 tetrahedra, and faces with four equivalent Cu(1)La4As4 tetrahedra. The Cu(1)-As(1) bond length is 2.50 Å. The Cu(1)-As(2) bond length is 2.53 Å. The Cu(1)-As(3) bond length is 2.51 Å. The Cu(1)-As(4) bond length is 2.51 Å. In the second Cu site, Cu(2) is bonded in a 9-coordinate geometry to two equivalent La(3), two equivalent La(4), one As(2), and four equivalent As(5) atoms. The Cu(2)-As(2) bond length is 2.47 Å. All Cu(2)-As(5) bond lengths are 2.53 Å. There are five inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to two equivalent La(3), two equivalent La(4), and four equivalent Cu(1) atoms. In the second As site, As(2) is bonded in a 9-coordinate geometry to two equivalent La(3), two equivalent La(4), one Cu(2), and four equivalent Cu(1) atoms. In the third As site, As(3) is bonded in a 8-coordinate geometry to two equivalent La(1), two equivalent La(2), and four equivalent Cu(1) atoms. In the fourth As site, As(4) is bonded in a 8-coordinate geometry to two equivalent La(1), two equivalent La(2), and four equivalent Cu(1) atoms. In the fifth As site, As(5) is bonded in a 7-coordinate geometry to one La(1), one La(2), one La(3), one La(4), one Cu(2), and two equivalent As(5) atoms. There is one shorter (2.56 Å) and one longer (2.75 Å) As(5)-As(5) bond length.