Ho15Si9C crystallizes in the hexagonal P6_3mc space group. There are four inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 2-coordinate geometry to one Si(2), three equivalent Si(1), and two equivalent C(1) atoms. In the second Ho site, Ho(2) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), and two equivalent Si(3) atoms. In the third Ho site, Ho(3) is bonded in a 5-coordinate geometry to two equivalent Si(2) and three equivalent Si(3) atoms. In the fourth Ho site, Ho(4) is bonded in a 6-coordinate geometry to two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. There are three inequivalent Si sites. In the first Si site, Si(2) is bonded in a 8-coordinate geometry to one Ho(1), one Ho(2), two equivalent Ho(3), and four equivalent Ho(4) atoms. In the second Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Ho(2), three equivalent Ho(3), and four equivalent Ho(4) atoms. In the third Si site, Si(1) is bonded in a 8-coordinate geometry to one Ho(2), three equivalent Ho(1), and four equivalent Ho(4) atoms. C(1) is bonded to six equivalent Ho(1) atoms to form face-sharing CHo6 octahedra.
Ho15Si9C crystallizes in the hexagonal P6_3mc space group. There are four inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 2-coordinate geometry to one Si(2), three equivalent Si(1), and two equivalent C(1) atoms. The Ho(1)-Si(2) bond length is 3.22 Å. There are two shorter (2.99 Å) and one longer (3.34 Å) Ho(1)-Si(1) bond length. There is one shorter (2.44 Å) and one longer (2.47 Å) Ho(1)-C(1) bond length. In the second Ho site, Ho(2) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), and two equivalent Si(3) atoms. The Ho(2)-Si(1) bond length is 2.92 Å. The Ho(2)-Si(2) bond length is 3.16 Å. Both Ho(2)-Si(3) bond lengths are 2.92 Å. In the third Ho site, Ho(3) is bonded in a 5-coordinate geometry to two equivalent Si(2) and three equivalent Si(3) atoms. Both Ho(3)-Si(2) bond lengths are 2.91 Å. There are a spread of Ho(3)-Si(3) bond distances ranging from 3.00-3.53 Å. In the fourth Ho site, Ho(4) is bonded in a 6-coordinate geometry to two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. There is one shorter (2.97 Å) and one longer (3.02 Å) Ho(4)-Si(1) bond length. There is one shorter (3.01 Å) and one longer (3.08 Å) Ho(4)-Si(2) bond length. There is one shorter (3.04 Å) and one longer (3.06 Å) Ho(4)-Si(3) bond length. There are three inequivalent Si sites. In the first Si site, Si(2) is bonded in a 8-coordinate geometry to one Ho(1), one Ho(2), two equivalent Ho(3), and four equivalent Ho(4) atoms. In the second Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Ho(2), three equivalent Ho(3), and four equivalent Ho(4) atoms. In the third Si site, Si(1) is bonded in a 8-coordinate geometry to one Ho(2), three equivalent Ho(1), and four equivalent Ho(4) atoms. C(1) is bonded to six equivalent Ho(1) atoms to form face-sharing CHo6 octahedra.