Ho5Co19P12 crystallizes in the hexagonal P-62m space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 15-coordinate geometry to three equivalent Co(3), six equivalent Co(1), and six equivalent P(1) atoms. In the second Ho site, Ho(2) is bonded in a 16-coordinate geometry to two equivalent Co(1), two equivalent Co(4), two equivalent Co(5), four equivalent Co(3), two equivalent P(3), and four equivalent P(2) atoms. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded to one Ho(2), two equivalent Ho(1), two equivalent P(1), and two equivalent P(3) atoms to form distorted CoHo3P4 tetrahedra that share corners with two equivalent Co(4)Ho2P4 tetrahedra, corners with two equivalent Co(3)Ho3P4 tetrahedra, corners with six equivalent Co(1)Ho3P4 tetrahedra,  an edgeedge with one Co(4)Ho2P4 tetrahedra, edges with two equivalent Co(1)Ho3P4 tetrahedra, edges with four equivalent Co(3)Ho3P4 tetrahedra, faces with two equivalent Co(3)Ho3P4 tetrahedra, and faces with three equivalent Co(1)Ho3P4 tetrahedra. In the second Co site, Co(2) is bonded in a 1-coordinate geometry to one P(3) and four equivalent P(1) atoms. In the third Co site, Co(3) is bonded to one Ho(1), two equivalent Ho(2), one P(2), one P(3), and two equivalent P(1) atoms to form distorted CoHo3P4 tetrahedra that share corners with two equivalent Co(4)Ho2P4 tetrahedra, corners with two equivalent Co(1)Ho3P4 tetrahedra, corners with five equivalent Co(3)Ho3P4 tetrahedra, edges with two equivalent Co(3)Ho3P4 tetrahedra, edges with four equivalent Co(1)Ho3P4 tetrahedra,  a faceface with one Co(3)Ho3P4 tetrahedra, faces with two equivalent Co(4)Ho2P4 tetrahedra, and faces with two equivalent Co(1)Ho3P4 tetrahedra. In the fourth Co site, Co(4) is bonded to two equivalent Ho(2), two equivalent P(1), and two equivalent P(2) atoms to form distorted CoHo2P4 tetrahedra that share corners with four equivalent Co(4)Ho2P4 tetrahedra, corners with four equivalent Co(1)Ho3P4 tetrahedra, corners with four equivalent Co(3)Ho3P4 tetrahedra, edges with two equivalent Co(1)Ho3P4 tetrahedra, and faces with four equivalent Co(3)Ho3P4 tetrahedra. In the fifth Co site, Co(5) is bonded in a distorted trigonal planar geometry to six equivalent Ho(2) and three equivalent P(2) atoms. There are three inequivalent P sites. In the first P site, P(3) is bonded in a 9-coordinate geometry to two equivalent Ho(2), one Co(2), two equivalent Co(3), and four equivalent Co(1) atoms. In the second P site, P(1) is bonded in a 9-coordinate geometry to two equivalent Ho(1), one Co(4), two equivalent Co(1), two equivalent Co(2), and two equivalent Co(3) atoms. In the third P site, P(2) is bonded in a 9-coordinate geometry to four equivalent Ho(2), one Co(5), two equivalent Co(3), and two equivalent Co(4) atoms.
Ho5Co19P12 crystallizes in the hexagonal P-62m space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 15-coordinate geometry to three equivalent Co(3), six equivalent Co(1), and six equivalent P(1) atoms. All Ho(1)-Co(3) bond lengths are 2.97 Å. All Ho(1)-Co(1) bond lengths are 2.97 Å. All Ho(1)-P(1) bond lengths are 2.79 Å. In the second Ho site, Ho(2) is bonded in a 16-coordinate geometry to two equivalent Co(1), two equivalent Co(4), two equivalent Co(5), four equivalent Co(3), two equivalent P(3), and four equivalent P(2) atoms. Both Ho(2)-Co(1) bond lengths are 3.05 Å. Both Ho(2)-Co(4) bond lengths are 2.97 Å. Both Ho(2)-Co(5) bond lengths are 2.88 Å. All Ho(2)-Co(3) bond lengths are 2.95 Å. Both Ho(2)-P(3) bond lengths are 2.82 Å. All Ho(2)-P(2) bond lengths are 2.85 Å. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded to one Ho(2), two equivalent Ho(1), two equivalent P(1), and two equivalent P(3) atoms to form distorted CoHo3P4 tetrahedra that share corners with two equivalent Co(4)Ho2P4 tetrahedra, corners with two equivalent Co(3)Ho3P4 tetrahedra, corners with six equivalent Co(1)Ho3P4 tetrahedra,  an edgeedge with one Co(4)Ho2P4 tetrahedra, edges with two equivalent Co(1)Ho3P4 tetrahedra, edges with four equivalent Co(3)Ho3P4 tetrahedra, faces with two equivalent Co(3)Ho3P4 tetrahedra, and faces with three equivalent Co(1)Ho3P4 tetrahedra. There is one shorter (2.21 Å) and one longer (2.25 Å) Co(1)-P(1) bond length. Both Co(1)-P(3) bond lengths are 2.32 Å. In the second Co site, Co(2) is bonded in a 1-coordinate geometry to one P(3) and four equivalent P(1) atoms. The Co(2)-P(3) bond length is 2.20 Å. All Co(2)-P(1) bond lengths are 2.58 Å. In the third Co site, Co(3) is bonded to one Ho(1), two equivalent Ho(2), one P(2), one P(3), and two equivalent P(1) atoms to form distorted CoHo3P4 tetrahedra that share corners with two equivalent Co(4)Ho2P4 tetrahedra, corners with two equivalent Co(1)Ho3P4 tetrahedra, corners with five equivalent Co(3)Ho3P4 tetrahedra, edges with two equivalent Co(3)Ho3P4 tetrahedra, edges with four equivalent Co(1)Ho3P4 tetrahedra,  a faceface with one Co(3)Ho3P4 tetrahedra, faces with two equivalent Co(4)Ho2P4 tetrahedra, and faces with two equivalent Co(1)Ho3P4 tetrahedra. The Co(3)-P(2) bond length is 2.24 Å. The Co(3)-P(3) bond length is 2.32 Å. Both Co(3)-P(1) bond lengths are 2.23 Å. In the fourth Co site, Co(4) is bonded to two equivalent Ho(2), two equivalent P(1), and two equivalent P(2) atoms to form distorted CoHo2P4 tetrahedra that share corners with four equivalent Co(4)Ho2P4 tetrahedra, corners with four equivalent Co(1)Ho3P4 tetrahedra, corners with four equivalent Co(3)Ho3P4 tetrahedra, edges with two equivalent Co(1)Ho3P4 tetrahedra, and faces with four equivalent Co(3)Ho3P4 tetrahedra. Both Co(4)-P(1) bond lengths are 2.17 Å. Both Co(4)-P(2) bond lengths are 2.21 Å. In the fifth Co site, Co(5) is bonded in a distorted trigonal planar geometry to six equivalent Ho(2) and three equivalent P(2) atoms. All Co(5)-P(2) bond lengths are 2.13 Å. There are three inequivalent P sites. In the first P site, P(3) is bonded in a 9-coordinate geometry to two equivalent Ho(2), one Co(2), two equivalent Co(3), and four equivalent Co(1) atoms. In the second P site, P(1) is bonded in a 9-coordinate geometry to two equivalent Ho(1), one Co(4), two equivalent Co(1), two equivalent Co(2), and two equivalent Co(3) atoms. In the third P site, P(2) is bonded in a 9-coordinate geometry to four equivalent Ho(2), one Co(5), two equivalent Co(3), and two equivalent Co(4) atoms.