Ho2ScNbO7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to two equivalent O(3), two equivalent O(4), and four equivalent O(1) atoms to form distorted HoO8 hexagonal bipyramids that share edges with two equivalent Ho(1)O8 hexagonal bipyramids, edges with two equivalent Sc(1)O6 octahedra, and edges with four equivalent Nb(1)O6 octahedra. In the second Ho site, Ho(2) is bonded in a body-centered cubic geometry to two equivalent O(2), two equivalent O(4), and four equivalent O(1) atoms. Sc(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form ScO6 octahedra that share corners with two equivalent Sc(1)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra, and edges with two equivalent Ho(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 53-60°. Nb(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Sc(1)O6 octahedra, and edges with four equivalent Ho(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 46-53°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ho(1), one Ho(2), one Sc(1), and one Nb(1) atom to form distorted OHo2ScNb tetrahedra that share corners with two equivalent O(2)Ho2Sc2 tetrahedra, corners with two equivalent O(4)Ho4 tetrahedra, corners with eight equivalent O(1)Ho2ScNb tetrahedra,  an edgeedge with one O(2)Ho2Sc2 tetrahedra,  an edgeedge with one O(4)Ho4 tetrahedra, and edges with two equivalent O(1)Ho2ScNb tetrahedra. In the second O site, O(2) is bonded to two equivalent Ho(2) and two equivalent Sc(1) atoms to form OHo2Sc2 tetrahedra that share corners with two equivalent O(4)Ho4 tetrahedra, corners with four equivalent O(2)Ho2Sc2 tetrahedra, corners with eight equivalent O(1)Ho2ScNb tetrahedra,  an edgeedge with one O(4)Ho4 tetrahedra, and edges with four equivalent O(1)Ho2ScNb tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ho(1) and two equivalent Nb(1) atoms. In the fourth O site, O(4) 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)Ho2Sc2 tetrahedra, corners with four equivalent O(4)Ho4 tetrahedra, corners with eight equivalent O(1)Ho2ScNb tetrahedra,  an edgeedge with one O(2)Ho2Sc2 tetrahedra, and edges with four equivalent O(1)Ho2ScNb tetrahedra.
Ho2ScNbO7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to two equivalent O(3), two equivalent O(4), and four equivalent O(1) atoms to form distorted HoO8 hexagonal bipyramids that share edges with two equivalent Ho(1)O8 hexagonal bipyramids, edges with two equivalent Sc(1)O6 octahedra, and edges with four equivalent Nb(1)O6 octahedra. Both Ho(1)-O(3) bond lengths are 2.56 Å. Both Ho(1)-O(4) bond lengths are 2.21 Å. All Ho(1)-O(1) bond lengths are 2.47 Å. In the second Ho site, Ho(2) is bonded in a body-centered cubic geometry to two equivalent O(2), two equivalent O(4), and four equivalent O(1) atoms. Both Ho(2)-O(2) bond lengths are 2.41 Å. Both Ho(2)-O(4) bond lengths are 2.29 Å. All Ho(2)-O(1) bond lengths are 2.52 Å. Sc(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form ScO6 octahedra that share corners with two equivalent Sc(1)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra, and edges with two equivalent Ho(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 53-60°. Both Sc(1)-O(2) bond lengths are 2.10 Å. All Sc(1)-O(1) bond lengths are 2.11 Å. Nb(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Sc(1)O6 octahedra, and edges with four equivalent Ho(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 46-53°. Both Nb(1)-O(3) bond lengths are 2.02 Å. All Nb(1)-O(1) bond lengths are 1.99 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ho(1), one Ho(2), one Sc(1), and one Nb(1) atom to form distorted OHo2ScNb tetrahedra that share corners with two equivalent O(2)Ho2Sc2 tetrahedra, corners with two equivalent O(4)Ho4 tetrahedra, corners with eight equivalent O(1)Ho2ScNb tetrahedra,  an edgeedge with one O(2)Ho2Sc2 tetrahedra,  an edgeedge with one O(4)Ho4 tetrahedra, and edges with two equivalent O(1)Ho2ScNb tetrahedra. In the second O site, O(2) is bonded to two equivalent Ho(2) and two equivalent Sc(1) atoms to form OHo2Sc2 tetrahedra that share corners with two equivalent O(4)Ho4 tetrahedra, corners with four equivalent O(2)Ho2Sc2 tetrahedra, corners with eight equivalent O(1)Ho2ScNb tetrahedra,  an edgeedge with one O(4)Ho4 tetrahedra, and edges with four equivalent O(1)Ho2ScNb tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ho(1) and two equivalent Nb(1) atoms. In the fourth O site, O(4) 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)Ho2Sc2 tetrahedra, corners with four equivalent O(4)Ho4 tetrahedra, corners with eight equivalent O(1)Ho2ScNb tetrahedra,  an edgeedge with one O(2)Ho2Sc2 tetrahedra, and edges with four equivalent O(1)Ho2ScNb tetrahedra.