Ho4CoB13 crystallizes in the tetragonal P4/mnc space group. Ho(1) is bonded in a 16-coordinate geometry to one Co(1), one B(1), six equivalent B(2), and eight equivalent B(3) atoms. Co(1) is bonded to four equivalent Ho(1) and eight equivalent B(3) atoms to form CoHo4B8 cuboctahedra that share corners with four equivalent B(1)Ho4B8 cuboctahedra and faces with two equivalent B(1)Ho4B8 cuboctahedra. There are three inequivalent B sites. In the first B site, B(1) is bonded to four equivalent Ho(1) and eight equivalent B(3) atoms to form BHo4B8 cuboctahedra that share corners with four equivalent Co(1)Ho4B8 cuboctahedra and faces with two equivalent Co(1)Ho4B8 cuboctahedra. In the second B site, B(2) is bonded in a 9-coordinate geometry to six equivalent Ho(1), one B(2), and two equivalent B(3) atoms. In the third B site, B(3) is bonded in a 9-coordinate geometry to four equivalent Ho(1), one Co(1), one B(1), one B(2), and two equivalent B(3) atoms.
Ho4CoB13 crystallizes in the tetragonal P4/mnc space group. Ho(1) is bonded in a 16-coordinate geometry to one Co(1), one B(1), six equivalent B(2), and eight equivalent B(3) atoms. The Ho(1)-Co(1) bond length is 2.68 Å. The Ho(1)-B(1) bond length is 2.65 Å. There are a spread of Ho(1)-B(2) bond distances ranging from 2.71-2.89 Å. There are a spread of Ho(1)-B(3) bond distances ranging from 2.56-2.68 Å. Co(1) is bonded to four equivalent Ho(1) and eight equivalent B(3) atoms to form CoHo4B8 cuboctahedra that share corners with four equivalent B(1)Ho4B8 cuboctahedra and faces with two equivalent B(1)Ho4B8 cuboctahedra. All Co(1)-B(3) bond lengths are 2.16 Å. There are three inequivalent B sites. In the first B site, B(1) is bonded to four equivalent Ho(1) and eight equivalent B(3) atoms to form BHo4B8 cuboctahedra that share corners with four equivalent Co(1)Ho4B8 cuboctahedra and faces with two equivalent Co(1)Ho4B8 cuboctahedra. All B(1)-B(3) bond lengths are 2.11 Å. In the second B site, B(2) is bonded in a 9-coordinate geometry to six equivalent Ho(1), one B(2), and two equivalent B(3) atoms. The B(2)-B(2) bond length is 1.87 Å. Both B(2)-B(3) bond lengths are 1.78 Å. In the third B site, B(3) is bonded in a 9-coordinate geometry to four equivalent Ho(1), one Co(1), one B(1), one B(2), and two equivalent B(3) atoms. Both B(3)-B(3) bond lengths are 1.80 Å.