Ho3CuSiSe7 crystallizes in the hexagonal P6_3 space group. Ho(1) is bonded in a 9-coordinate geometry to one Cu(1), one Se(3), three equivalent Se(1), and four equivalent Se(2) atoms. Cu(1) is bonded in a trigonal planar geometry to three equivalent Ho(1) and three equivalent Se(2) atoms. Si(1) is bonded in a tetrahedral geometry to one Se(3) and three equivalent Se(1) atoms. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Ho(1) and one Si(1) atom. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to four equivalent Ho(1) and one Cu(1) atom. In the third Se site, Se(3) is bonded in a tetrahedral geometry to three equivalent Ho(1) and one Si(1) atom.
Ho3CuSiSe7 crystallizes in the hexagonal P6_3 space group. Ho(1) is bonded in a 9-coordinate geometry to one Cu(1), one Se(3), three equivalent Se(1), and four equivalent Se(2) atoms. The Ho(1)-Cu(1) bond length is 3.23 Å. The Ho(1)-Se(3) bond length is 3.09 Å. There are a spread of Ho(1)-Se(1) bond distances ranging from 2.92-3.17 Å. There are a spread of Ho(1)-Se(2) bond distances ranging from 2.87-3.34 Å. Cu(1) is bonded in a trigonal planar geometry to three equivalent Ho(1) and three equivalent Se(2) atoms. All Cu(1)-Se(2) bond lengths are 2.36 Å. Si(1) is bonded in a tetrahedral geometry to one Se(3) and three equivalent Se(1) atoms. The Si(1)-Se(3) bond length is 2.28 Å. All Si(1)-Se(1) bond lengths are 2.31 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Ho(1) and one Si(1) atom. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to four equivalent Ho(1) and one Cu(1) atom. In the third Se site, Se(3) is bonded in a tetrahedral geometry to three equivalent Ho(1) and one Si(1) atom.