Ho3Co2Si7 crystallizes in the orthorhombic Amm2 space group. There are three inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 14-coordinate geometry to four equivalent Co(1), two equivalent Si(4), two equivalent Si(5), two equivalent Si(7), and four equivalent Si(2) atoms. In the second Ho site, Ho(2) is bonded in a 14-coordinate geometry to four equivalent Co(2), two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), and four equivalent Si(4) atoms. In the third Ho site, Ho(3) is bonded to two equivalent Si(1), two equivalent Si(3), two equivalent Si(5), two equivalent Si(7), and four equivalent Si(6) atoms to form a mixture of distorted face and corner-sharing HoSi12 cuboctahedra. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a 5-coordinate geometry to four equivalent Ho(1), one Si(2), two equivalent Si(5), and two equivalent Si(7) atoms. In the second Co site, Co(2) is bonded in a 5-coordinate geometry to four equivalent Ho(2), one Si(4), two equivalent Si(1), and two equivalent Si(3) atoms. There are seven inequivalent Si sites. In the first Si site, Si(1) is bonded in a 12-coordinate geometry to two equivalent Ho(2), two equivalent Ho(3), two equivalent Co(2), two equivalent Si(6), and four equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Ho(2), four equivalent Ho(1), one Co(1), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 12-coordinate geometry to two equivalent Ho(2), two equivalent Ho(3), two equivalent Co(2), two equivalent Si(6), and four equivalent Si(1) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Ho(1), four equivalent Ho(2), one Co(2), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 6-coordinate geometry to two equivalent Ho(1), two equivalent Ho(3), and two equivalent Co(1) atoms. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to four equivalent Ho(3), two equivalent Si(1), and two equivalent Si(3) atoms. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to two equivalent Ho(1), two equivalent Ho(3), and two equivalent Co(1) atoms.
Ho3Co2Si7 crystallizes in the orthorhombic Amm2 space group. There are three inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 14-coordinate geometry to four equivalent Co(1), two equivalent Si(4), two equivalent Si(5), two equivalent Si(7), and four equivalent Si(2) atoms. All Ho(1)-Co(1) bond lengths are 3.14 Å. Both Ho(1)-Si(4) bond lengths are 3.07 Å. Both Ho(1)-Si(5) bond lengths are 3.09 Å. Both Ho(1)-Si(7) bond lengths are 3.07 Å. All Ho(1)-Si(2) bond lengths are 2.97 Å. In the second Ho site, Ho(2) is bonded in a 14-coordinate geometry to four equivalent Co(2), two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), and four equivalent Si(4) atoms. All Ho(2)-Co(2) bond lengths are 3.13 Å. Both Ho(2)-Si(1) bond lengths are 3.08 Å. Both Ho(2)-Si(2) bond lengths are 3.08 Å. Both Ho(2)-Si(3) bond lengths are 3.06 Å. All Ho(2)-Si(4) bond lengths are 2.98 Å. In the third Ho site, Ho(3) is bonded to two equivalent Si(1), two equivalent Si(3), two equivalent Si(5), two equivalent Si(7), and four equivalent Si(6) atoms to form a mixture of distorted face and corner-sharing HoSi12 cuboctahedra. Both Ho(3)-Si(1) bond lengths are 2.97 Å. Both Ho(3)-Si(3) bond lengths are 2.99 Å. Both Ho(3)-Si(5) bond lengths are 2.93 Å. Both Ho(3)-Si(7) bond lengths are 2.95 Å. All Ho(3)-Si(6) bond lengths are 2.85 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a 5-coordinate geometry to four equivalent Ho(1), one Si(2), two equivalent Si(5), and two equivalent Si(7) atoms. The Co(1)-Si(2) bond length is 2.25 Å. Both Co(1)-Si(5) bond lengths are 2.22 Å. Both Co(1)-Si(7) bond lengths are 2.25 Å. In the second Co site, Co(2) is bonded in a 5-coordinate geometry to four equivalent Ho(2), one Si(4), two equivalent Si(1), and two equivalent Si(3) atoms. The Co(2)-Si(4) bond length is 2.26 Å. Both Co(2)-Si(1) bond lengths are 2.22 Å. Both Co(2)-Si(3) bond lengths are 2.25 Å. There are seven inequivalent Si sites. In the first Si site, Si(1) is bonded in a 12-coordinate geometry to two equivalent Ho(2), two equivalent Ho(3), two equivalent Co(2), two equivalent Si(6), and four equivalent Si(3) atoms. Both Si(1)-Si(6) bond lengths are 2.74 Å. All Si(1)-Si(3) bond lengths are 2.83 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Ho(2), four equivalent Ho(1), one Co(1), and two equivalent Si(4) atoms. Both Si(2)-Si(4) bond lengths are 2.44 Å. In the third Si site, Si(3) is bonded in a 12-coordinate geometry to two equivalent Ho(2), two equivalent Ho(3), two equivalent Co(2), two equivalent Si(6), and four equivalent Si(1) atoms. Both Si(3)-Si(6) bond lengths are 2.72 Å. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Ho(1), four equivalent Ho(2), one Co(2), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 6-coordinate geometry to two equivalent Ho(1), two equivalent Ho(3), and two equivalent Co(1) atoms. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to four equivalent Ho(3), two equivalent Si(1), and two equivalent Si(3) atoms. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to two equivalent Ho(1), two equivalent Ho(3), and two equivalent Co(1) atoms.