TbB4 crystallizes in the tetragonal P4/mbm space group. Tb(1) is bonded in a 8-coordinate geometry to four equivalent B(1) and four equivalent B(3) atoms. There are three inequivalent B sites. In the first B site, B(2) is bonded in a 5-coordinate geometry to one B(2) and four equivalent B(1) atoms. In the second B site, B(1) is bonded in a 6-coordinate geometry to two equivalent Tb(1), two equivalent B(1), and two equivalent B(2) atoms. In the third B site, B(3) is bonded in a 5-coordinate geometry to four equivalent Tb(1) and one B(3) atom.
TbB4 crystallizes in the tetragonal P4/mbm space group. Tb(1) is bonded in a 8-coordinate geometry to four equivalent B(1) and four equivalent B(3) atoms. There are two shorter (2.59 Å) and two longer (2.60 Å) Tb(1)-B(1) bond lengths. All Tb(1)-B(3) bond lengths are 2.80 Å. There are three inequivalent B sites. In the first B site, B(2) is bonded in a 5-coordinate geometry to one B(2) and four equivalent B(1) atoms. The B(2)-B(2) bond length is 1.62 Å. All B(2)-B(1) bond lengths are 1.76 Å. In the second B site, B(1) is bonded in a 6-coordinate geometry to two equivalent Tb(1), two equivalent B(1), and two equivalent B(2) atoms. Both B(1)-B(1) bond lengths are 1.68 Å. In the third B site, B(3) is bonded in a 5-coordinate geometry to four equivalent Tb(1) and one B(3) atom. The B(3)-B(3) bond length is 1.55 Å.