MgHo2Se4 crystallizes in the orthorhombic Pnma space group. Mg(1) is bonded in a trigonal pyramidal geometry to one Se(2), one Se(3), and two equivalent Se(1) atoms. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 7-coordinate geometry to one Se(2), two equivalent Se(3), and four equivalent Se(1) atoms. In the second Ho site, Ho(2) is bonded in a 6-coordinate geometry to one Se(2), one Se(3), and four equivalent Se(1) atoms. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one Mg(1), two equivalent Ho(1), and two equivalent Ho(2) atoms. In the second Se site, Se(2) is bonded in a T-shaped geometry to one Mg(1), one Ho(1), and one Ho(2) atom. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ho(2), and two equivalent Ho(1) atoms.
MgHo2Se4 crystallizes in the orthorhombic Pnma space group. Mg(1) is bonded in a trigonal pyramidal geometry to one Se(2), one Se(3), and two equivalent Se(1) atoms. The Mg(1)-Se(2) bond length is 2.46 Å. The Mg(1)-Se(3) bond length is 2.68 Å. Both Mg(1)-Se(1) bond lengths are 2.63 Å. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 7-coordinate geometry to one Se(2), two equivalent Se(3), and four equivalent Se(1) atoms. The Ho(1)-Se(2) bond length is 2.82 Å. Both Ho(1)-Se(3) bond lengths are 2.78 Å. There are two shorter (3.10 Å) and two longer (3.20 Å) Ho(1)-Se(1) bond lengths. In the second Ho site, Ho(2) is bonded in a 6-coordinate geometry to one Se(2), one Se(3), and four equivalent Se(1) atoms. The Ho(2)-Se(2) bond length is 2.67 Å. The Ho(2)-Se(3) bond length is 2.80 Å. There are two shorter (2.91 Å) and two longer (2.96 Å) Ho(2)-Se(1) bond lengths. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one Mg(1), two equivalent Ho(1), and two equivalent Ho(2) atoms. In the second Se site, Se(2) is bonded in a T-shaped geometry to one Mg(1), one Ho(1), and one Ho(2) atom. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ho(2), and two equivalent Ho(1) atoms.