Ho3Cu4Si4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 12-coordinate geometry to six equivalent Cu(1), two equivalent Si(2), and four equivalent Si(1) atoms. In the second Ho site, Ho(2) is bonded to two equivalent Si(2) and four equivalent Si(1) atoms to form distorted edge-sharing HoSi6 octahedra. Cu(1) is bonded in a 8-coordinate geometry to three equivalent Ho(1), one Cu(1), one Si(1), and three equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Ho(2), four equivalent Ho(1), two equivalent Cu(1), and one Si(1) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Ho(2), two equivalent Ho(1), and six equivalent Cu(1) atoms.
Ho3Cu4Si4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 12-coordinate geometry to six equivalent Cu(1), two equivalent Si(2), and four equivalent Si(1) atoms. There are a spread of Ho(1)-Cu(1) bond distances ranging from 2.92-2.99 Å. There is one shorter (2.92 Å) and one longer (2.93 Å) Ho(1)-Si(2) bond length. All Ho(1)-Si(1) bond lengths are 2.96 Å. In the second Ho site, Ho(2) is bonded to two equivalent Si(2) and four equivalent Si(1) atoms to form distorted edge-sharing HoSi6 octahedra. Both Ho(2)-Si(2) bond lengths are 2.93 Å. All Ho(2)-Si(1) bond lengths are 2.90 Å. Cu(1) is bonded in a 8-coordinate geometry to three equivalent Ho(1), one Cu(1), one Si(1), and three equivalent Si(2) atoms. The Cu(1)-Cu(1) bond length is 2.46 Å. The Cu(1)-Si(1) bond length is 2.43 Å. There are a spread of Cu(1)-Si(2) bond distances ranging from 2.47-2.55 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Ho(2), four equivalent Ho(1), two equivalent Cu(1), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.40 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Ho(2), two equivalent Ho(1), and six equivalent Cu(1) atoms.