TbH3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. Tb(1) is bonded in a distorted body-centered cubic geometry to six equivalent H(1) and eight equivalent H(2) atoms. There are two inequivalent H sites. In the first H site, H(1) is bonded to six equivalent Tb(1) atoms to form HTb6 octahedra that share corners with six equivalent H(1)Tb6 octahedra, corners with twenty-four equivalent H(2)Tb4 tetrahedra, edges with twelve equivalent H(1)Tb6 octahedra, and faces with eight equivalent H(2)Tb4 tetrahedra. The corner-sharing octahedra are not tilted. In the second H site, H(2) is bonded to four equivalent Tb(1) atoms to form HTb4 tetrahedra that share corners with twelve equivalent H(1)Tb6 octahedra, corners with sixteen equivalent H(2)Tb4 tetrahedra, edges with six equivalent H(2)Tb4 tetrahedra, and faces with four equivalent H(1)Tb6 octahedra. The corner-sharing octahedral tilt angles are 55°.
TbH3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. Tb(1) is bonded in a distorted body-centered cubic geometry to six equivalent H(1) and eight equivalent H(2) atoms. All Tb(1)-H(1) bond lengths are 2.59 Å. All Tb(1)-H(2) bond lengths are 2.24 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded to six equivalent Tb(1) atoms to form HTb6 octahedra that share corners with six equivalent H(1)Tb6 octahedra, corners with twenty-four equivalent H(2)Tb4 tetrahedra, edges with twelve equivalent H(1)Tb6 octahedra, and faces with eight equivalent H(2)Tb4 tetrahedra. The corner-sharing octahedra are not tilted. In the second H site, H(2) is bonded to four equivalent Tb(1) atoms to form HTb4 tetrahedra that share corners with twelve equivalent H(1)Tb6 octahedra, corners with sixteen equivalent H(2)Tb4 tetrahedra, edges with six equivalent H(2)Tb4 tetrahedra, and faces with four equivalent H(1)Tb6 octahedra. The corner-sharing octahedral tilt angles are 55°.