Tm4CoB13 crystallizes in the tetragonal P4/mnc space group. Tm(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 Tm(1) and eight equivalent B(3) atoms to form CoTm4B8 cuboctahedra that share corners with four equivalent B(1)Tm4B8 cuboctahedra and faces with two equivalent B(1)Tm4B8 cuboctahedra. There are three inequivalent B sites. In the first B site, B(1) is bonded to four equivalent Tm(1) and eight equivalent B(3) atoms to form BTm4B8 cuboctahedra that share corners with four equivalent Co(1)Tm4B8 cuboctahedra and faces with two equivalent Co(1)Tm4B8 cuboctahedra. In the second B site, B(2) is bonded in a 9-coordinate geometry to six equivalent Tm(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 Tm(1), one Co(1), one B(1), one B(2), and two equivalent B(3) atoms.
Tm4CoB13 crystallizes in the tetragonal P4/mnc space group. Tm(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 Tm(1)-Co(1) bond length is 2.67 Å. The Tm(1)-B(1) bond length is 2.64 Å. There are a spread of Tm(1)-B(2) bond distances ranging from 2.69-2.88 Å. There are a spread of Tm(1)-B(3) bond distances ranging from 2.54-2.67 Å. Co(1) is bonded to four equivalent Tm(1) and eight equivalent B(3) atoms to form CoTm4B8 cuboctahedra that share corners with four equivalent B(1)Tm4B8 cuboctahedra and faces with two equivalent B(1)Tm4B8 cuboctahedra. All Co(1)-B(3) bond lengths are 2.15 Å. There are three inequivalent B sites. In the first B site, B(1) is bonded to four equivalent Tm(1) and eight equivalent B(3) atoms to form BTm4B8 cuboctahedra that share corners with four equivalent Co(1)Tm4B8 cuboctahedra and faces with two equivalent Co(1)Tm4B8 cuboctahedra. All B(1)-B(3) bond lengths are 2.10 Å. In the second B site, B(2) is bonded in a 9-coordinate geometry to six equivalent Tm(1), one B(2), and two equivalent B(3) atoms. The B(2)-B(2) bond length is 1.85 Å. Both B(2)-B(3) bond lengths are 1.77 Å. In the third B site, B(3) is bonded in a 9-coordinate geometry to four equivalent Tm(1), one Co(1), one B(1), one B(2), and two equivalent B(3) atoms. Both B(3)-B(3) bond lengths are 1.79 Å.