Ho3ReO7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 6-coordinate geometry to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. In the second Ho site, Ho(2) is bonded to one O(2), one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted HoO7 pentagonal bipyramids that share corners with two equivalent Re(1)O6 octahedra,  a cornercorner with one Ho(2)O7 pentagonal bipyramid, edges with two equivalent Re(1)O6 octahedra, and edges with three equivalent Ho(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 41-49°. Re(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form ReO6 octahedra that share corners with two equivalent Re(1)O6 octahedra, corners with four equivalent Ho(2)O7 pentagonal bipyramids, and edges with four equivalent Ho(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Ho(2) and one Re(1) atom. In the second O site, O(2) is bonded to two equivalent Ho(2) and two equivalent Re(1) atoms to form distorted OHo2Re2 tetrahedra that share corners with two equivalent O(2)Ho2Re2 tetrahedra, corners with two equivalent O(3)Ho4 tetrahedra, corners with four equivalent O(4)Ho3Re tetrahedra,  an edgeedge with one O(5)Ho4 tetrahedra, and edges with two equivalent O(4)Ho3Re tetrahedra. In the third O site, O(3) is bonded to two equivalent Ho(1) and two equivalent Ho(2) atoms to form OHo4 tetrahedra that share corners with two equivalent O(2)Ho2Re2 tetrahedra, corners with two equivalent O(3)Ho4 tetrahedra, corners with four equivalent O(4)Ho3Re tetrahedra, corners with four equivalent O(5)Ho4 tetrahedra,  an edgeedge with one O(5)Ho4 tetrahedra, and edges with two equivalent O(4)Ho3Re tetrahedra. In the fourth O site, O(4) is bonded to one Ho(1), two equivalent Ho(2), and one Re(1) atom to form OHo3Re tetrahedra that share corners with two equivalent O(2)Ho2Re2 tetrahedra, corners with two equivalent O(4)Ho3Re tetrahedra, corners with two equivalent O(3)Ho4 tetrahedra, corners with two equivalent O(5)Ho4 tetrahedra,  an edgeedge with one O(2)Ho2Re2 tetrahedra,  an edgeedge with one O(4)Ho3Re tetrahedra,  an edgeedge with one O(3)Ho4 tetrahedra, and  an edgeedge with one O(5)Ho4 tetrahedra. In the fifth O site, O(5) is bonded to two equivalent Ho(1) and two equivalent Ho(2) atoms to form OHo4 tetrahedra that share corners with two equivalent O(5)Ho4 tetrahedra, corners with four equivalent O(4)Ho3Re tetrahedra, corners with four equivalent O(3)Ho4 tetrahedra,  an edgeedge with one O(2)Ho2Re2 tetrahedra,  an edgeedge with one O(3)Ho4 tetrahedra, and edges with two equivalent O(4)Ho3Re tetrahedra.
Ho3ReO7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 6-coordinate geometry to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. Both Ho(1)-O(3) bond lengths are 2.31 Å. Both Ho(1)-O(4) bond lengths are 2.35 Å. Both Ho(1)-O(5) bond lengths are 2.36 Å. In the second Ho site, Ho(2) is bonded to one O(2), one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted HoO7 pentagonal bipyramids that share corners with two equivalent Re(1)O6 octahedra,  a cornercorner with one Ho(2)O7 pentagonal bipyramid, edges with two equivalent Re(1)O6 octahedra, and edges with three equivalent Ho(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 41-49°. The Ho(2)-O(2) bond length is 2.42 Å. The Ho(2)-O(3) bond length is 2.28 Å. The Ho(2)-O(5) bond length is 2.21 Å. There is one shorter (2.27 Å) and one longer (2.38 Å) Ho(2)-O(1) bond length. There is one shorter (2.27 Å) and one longer (2.39 Å) Ho(2)-O(4) bond length. Re(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form ReO6 octahedra that share corners with two equivalent Re(1)O6 octahedra, corners with four equivalent Ho(2)O7 pentagonal bipyramids, and edges with four equivalent Ho(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. Both Re(1)-O(1) bond lengths are 1.93 Å. Both Re(1)-O(2) bond lengths are 2.00 Å. Both Re(1)-O(4) bond lengths are 2.02 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Ho(2) and one Re(1) atom. In the second O site, O(2) is bonded to two equivalent Ho(2) and two equivalent Re(1) atoms to form distorted OHo2Re2 tetrahedra that share corners with two equivalent O(2)Ho2Re2 tetrahedra, corners with two equivalent O(3)Ho4 tetrahedra, corners with four equivalent O(4)Ho3Re tetrahedra,  an edgeedge with one O(5)Ho4 tetrahedra, and edges with two equivalent O(4)Ho3Re tetrahedra. In the third O site, O(3) is bonded to two equivalent Ho(1) and two equivalent Ho(2) atoms to form OHo4 tetrahedra that share corners with two equivalent O(2)Ho2Re2 tetrahedra, corners with two equivalent O(3)Ho4 tetrahedra, corners with four equivalent O(4)Ho3Re tetrahedra, corners with four equivalent O(5)Ho4 tetrahedra,  an edgeedge with one O(5)Ho4 tetrahedra, and edges with two equivalent O(4)Ho3Re tetrahedra. In the fourth O site, O(4) is bonded to one Ho(1), two equivalent Ho(2), and one Re(1) atom to form OHo3Re tetrahedra that share corners with two equivalent O(2)Ho2Re2 tetrahedra, corners with two equivalent O(4)Ho3Re tetrahedra, corners with two equivalent O(3)Ho4 tetrahedra, corners with two equivalent O(5)Ho4 tetrahedra,  an edgeedge with one O(2)Ho2Re2 tetrahedra,  an edgeedge with one O(4)Ho3Re tetrahedra,  an edgeedge with one O(3)Ho4 tetrahedra, and  an edgeedge with one O(5)Ho4 tetrahedra. In the fifth O site, O(5) is bonded to two equivalent Ho(1) and two equivalent Ho(2) atoms to form OHo4 tetrahedra that share corners with two equivalent O(5)Ho4 tetrahedra, corners with four equivalent O(4)Ho3Re tetrahedra, corners with four equivalent O(3)Ho4 tetrahedra,  an edgeedge with one O(2)Ho2Re2 tetrahedra,  an edgeedge with one O(3)Ho4 tetrahedra, and edges with two equivalent O(4)Ho3Re tetrahedra.