Ho9CSb5O4 crystallizes in the tetragonal P4/n space group. There are three inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a distorted single-bond geometry to one C(1), one Sb(1), and four equivalent Sb(2) atoms. In the second Ho site, Ho(2) is bonded in a distorted single-bond geometry to one Sb(1), four equivalent Sb(2), and one O(1) atom. In the third Ho site, Ho(3) is bonded in a 4-coordinate geometry to one C(1), two equivalent Sb(2), and three equivalent O(1) atoms. C(1) is bonded to one Ho(1) and four equivalent Ho(3) atoms to form distorted CHo5 trigonal bipyramids that share  a cornercorner with one Sb(1)Ho5 square pyramid, corners with four equivalent O(1)Ho4 tetrahedra, and edges with four equivalent O(1)Ho4 tetrahedra. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one Ho(1) and four equivalent Ho(2) atoms to form SbHo5 square pyramids that share corners with four equivalent O(1)Ho4 tetrahedra and  a cornercorner with one C(1)Ho5 trigonal bipyramid. In the second Sb site, Sb(2) is bonded in a 7-coordinate geometry to one Ho(1), two equivalent Ho(3), and four equivalent Ho(2) atoms. O(1) is bonded to one Ho(2) and three equivalent Ho(3) atoms to form OHo4 tetrahedra that share  a cornercorner with one Sb(1)Ho5 square pyramid, corners with four equivalent O(1)Ho4 tetrahedra,  a cornercorner with one C(1)Ho5 trigonal bipyramid,  an edgeedge with one O(1)Ho4 tetrahedra, and  an edgeedge with one C(1)Ho5 trigonal bipyramid.
Ho9CSb5O4 crystallizes in the tetragonal P4/n space group. There are three inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a distorted single-bond geometry to one C(1), one Sb(1), and four equivalent Sb(2) atoms. The Ho(1)-C(1) bond length is 2.26 Å. The Ho(1)-Sb(1) bond length is 3.23 Å. All Ho(1)-Sb(2) bond lengths are 3.19 Å. In the second Ho site, Ho(2) is bonded in a distorted single-bond geometry to one Sb(1), four equivalent Sb(2), and one O(1) atom. The Ho(2)-Sb(1) bond length is 3.11 Å. There are a spread of Ho(2)-Sb(2) bond distances ranging from 3.12-3.18 Å. The Ho(2)-O(1) bond length is 2.21 Å. In the third Ho site, Ho(3) is bonded in a 4-coordinate geometry to one C(1), two equivalent Sb(2), and three equivalent O(1) atoms. The Ho(3)-C(1) bond length is 2.42 Å. There is one shorter (3.39 Å) and one longer (3.44 Å) Ho(3)-Sb(2) bond length. There are a spread of Ho(3)-O(1) bond distances ranging from 2.21-2.31 Å. C(1) is bonded to one Ho(1) and four equivalent Ho(3) atoms to form distorted CHo5 trigonal bipyramids that share  a cornercorner with one Sb(1)Ho5 square pyramid, corners with four equivalent O(1)Ho4 tetrahedra, and edges with four equivalent O(1)Ho4 tetrahedra. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one Ho(1) and four equivalent Ho(2) atoms to form SbHo5 square pyramids that share corners with four equivalent O(1)Ho4 tetrahedra and  a cornercorner with one C(1)Ho5 trigonal bipyramid. In the second Sb site, Sb(2) is bonded in a 7-coordinate geometry to one Ho(1), two equivalent Ho(3), and four equivalent Ho(2) atoms. O(1) is bonded to one Ho(2) and three equivalent Ho(3) atoms to form OHo4 tetrahedra that share  a cornercorner with one Sb(1)Ho5 square pyramid, corners with four equivalent O(1)Ho4 tetrahedra,  a cornercorner with one C(1)Ho5 trigonal bipyramid,  an edgeedge with one O(1)Ho4 tetrahedra, and  an edgeedge with one C(1)Ho5 trigonal bipyramid.