LaCo8P5 crystallizes in the orthorhombic Pmmn space group. La(1) is bonded in a 17-coordinate geometry to one Co(4), two equivalent Co(1), two equivalent Co(5), four equivalent Co(2), four equivalent P(1), and four equivalent P(2) atoms. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded to one La(1), one P(3), and three equivalent P(2) atoms to form distorted CoLaP4 tetrahedra that share  a cornercorner with one Co(5)La2P4 tetrahedra, corners with two equivalent Co(1)LaP4 tetrahedra, corners with three equivalent Co(2)La2P4 tetrahedra, edges with two equivalent Co(2)La2P4 tetrahedra, edges with three equivalent Co(1)LaP4 tetrahedra, and faces with two equivalent Co(5)La2P4 tetrahedra. In the second Co site, Co(2) is bonded to two equivalent La(1), one P(2), and three equivalent P(1) atoms to form distorted CoLa2P4 tetrahedra that share corners with two equivalent Co(2)La2P4 tetrahedra, corners with two equivalent Co(5)La2P4 tetrahedra, corners with three equivalent Co(1)LaP4 tetrahedra, edges with two equivalent Co(1)LaP4 tetrahedra, edges with five equivalent Co(2)La2P4 tetrahedra, and  a faceface with one Co(5)La2P4 tetrahedra. In the third Co site, Co(3) is bonded in a 5-coordinate geometry to one P(1), two equivalent P(2), and two equivalent P(3) atoms. In the fourth Co site, Co(4) is bonded in a 5-coordinate geometry to one La(1), one P(3), and four equivalent P(1) atoms. In the fifth Co site, Co(5) is bonded to two equivalent La(1), two equivalent P(2), and two equivalent P(3) atoms to form distorted CoLa2P4 tetrahedra that share corners with two equivalent Co(1)LaP4 tetrahedra, corners with four equivalent Co(2)La2P4 tetrahedra, edges with two equivalent Co(5)La2P4 tetrahedra, faces with two equivalent Co(2)La2P4 tetrahedra, and faces with four equivalent Co(1)LaP4 tetrahedra. There are three inequivalent P sites. In the first P site, P(1) is bonded in a 9-coordinate geometry to two equivalent La(1), one Co(3), two equivalent Co(4), three equivalent Co(2), and one P(1) atom. In the second P site, P(2) is bonded in a 9-coordinate geometry to two equivalent La(1), one Co(2), one Co(5), two equivalent Co(3), and three equivalent Co(1) atoms. In the third P site, P(3) is bonded in a 9-coordinate geometry to one Co(4), two equivalent Co(1), two equivalent Co(5), and four equivalent Co(3) atoms.
LaCo8P5 crystallizes in the orthorhombic Pmmn space group. La(1) is bonded in a 17-coordinate geometry to one Co(4), two equivalent Co(1), two equivalent Co(5), four equivalent Co(2), four equivalent P(1), and four equivalent P(2) atoms. The La(1)-Co(4) bond length is 3.06 Å. Both La(1)-Co(1) bond lengths are 3.32 Å. Both La(1)-Co(5) bond lengths are 3.16 Å. All La(1)-Co(2) bond lengths are 3.28 Å. All La(1)-P(1) bond lengths are 3.12 Å. All La(1)-P(2) bond lengths are 3.06 Å. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded to one La(1), one P(3), and three equivalent P(2) atoms to form distorted CoLaP4 tetrahedra that share  a cornercorner with one Co(5)La2P4 tetrahedra, corners with two equivalent Co(1)LaP4 tetrahedra, corners with three equivalent Co(2)La2P4 tetrahedra, edges with two equivalent Co(2)La2P4 tetrahedra, edges with three equivalent Co(1)LaP4 tetrahedra, and faces with two equivalent Co(5)La2P4 tetrahedra. The Co(1)-P(3) bond length is 2.13 Å. There is one shorter (2.21 Å) and two longer (2.22 Å) Co(1)-P(2) bond lengths. In the second Co site, Co(2) is bonded to two equivalent La(1), one P(2), and three equivalent P(1) atoms to form distorted CoLa2P4 tetrahedra that share corners with two equivalent Co(2)La2P4 tetrahedra, corners with two equivalent Co(5)La2P4 tetrahedra, corners with three equivalent Co(1)LaP4 tetrahedra, edges with two equivalent Co(1)LaP4 tetrahedra, edges with five equivalent Co(2)La2P4 tetrahedra, and  a faceface with one Co(5)La2P4 tetrahedra. The Co(2)-P(2) bond length is 2.22 Å. There is one shorter (2.17 Å) and two longer (2.24 Å) Co(2)-P(1) bond lengths. In the third Co site, Co(3) is bonded in a 5-coordinate geometry to one P(1), two equivalent P(2), and two equivalent P(3) atoms. The Co(3)-P(1) bond length is 2.20 Å. Both Co(3)-P(2) bond lengths are 2.50 Å. Both Co(3)-P(3) bond lengths are 2.48 Å. In the fourth Co site, Co(4) is bonded in a 5-coordinate geometry to one La(1), one P(3), and four equivalent P(1) atoms. The Co(4)-P(3) bond length is 2.15 Å. All Co(4)-P(1) bond lengths are 2.34 Å. In the fifth Co site, Co(5) is bonded to two equivalent La(1), two equivalent P(2), and two equivalent P(3) atoms to form distorted CoLa2P4 tetrahedra that share corners with two equivalent Co(1)LaP4 tetrahedra, corners with four equivalent Co(2)La2P4 tetrahedra, edges with two equivalent Co(5)La2P4 tetrahedra, faces with two equivalent Co(2)La2P4 tetrahedra, and faces with four equivalent Co(1)LaP4 tetrahedra. Both Co(5)-P(2) bond lengths are 2.26 Å. Both Co(5)-P(3) bond lengths are 2.27 Å. There are three inequivalent P sites. In the first P site, P(1) is bonded in a 9-coordinate geometry to two equivalent La(1), one Co(3), two equivalent Co(4), three equivalent Co(2), and one P(1) atom. The P(1)-P(1) bond length is 2.50 Å. In the second P site, P(2) is bonded in a 9-coordinate geometry to two equivalent La(1), one Co(2), one Co(5), two equivalent Co(3), and three equivalent Co(1) atoms. In the third P site, P(3) is bonded in a 9-coordinate geometry to one Co(4), two equivalent Co(1), two equivalent Co(5), and four equivalent Co(3) atoms.