TbOsGa3 crystallizes in the cubic Pm-3m space group. Tb(1) is bonded in a 14-coordinate geometry to four equivalent Os(1), two equivalent Ga(1), and eight equivalent Ga(2) atoms. Os(1) is bonded to four equivalent Tb(1) and eight equivalent Ga(2) atoms to form distorted OsTb4Ga8 cuboctahedra that share corners with four equivalent Os(1)Tb4Ga8 cuboctahedra, edges with four equivalent Ga(1)Tb6 octahedra, and faces with eight equivalent Os(1)Tb4Ga8 cuboctahedra. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to six equivalent Tb(1) atoms to form GaTb6 octahedra that share corners with six equivalent Ga(1)Tb6 octahedra and edges with twelve equivalent Os(1)Tb4Ga8 cuboctahedra. The corner-sharing octahedra are not tilted. In the second Ga site, Ga(2) is bonded in a 9-coordinate geometry to three equivalent Tb(1), three equivalent Os(1), and three equivalent Ga(2) atoms.
TbOsGa3 crystallizes in the cubic Pm-3m space group. Tb(1) is bonded in a 14-coordinate geometry to four equivalent Os(1), two equivalent Ga(1), and eight equivalent Ga(2) atoms. All Tb(1)-Os(1) bond lengths are 3.20 Å. Both Tb(1)-Ga(1) bond lengths are 3.20 Å. All Tb(1)-Ga(2) bond lengths are 2.96 Å. Os(1) is bonded to four equivalent Tb(1) and eight equivalent Ga(2) atoms to form distorted OsTb4Ga8 cuboctahedra that share corners with four equivalent Os(1)Tb4Ga8 cuboctahedra, edges with four equivalent Ga(1)Tb6 octahedra, and faces with eight equivalent Os(1)Tb4Ga8 cuboctahedra. All Os(1)-Ga(2) bond lengths are 2.65 Å. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to six equivalent Tb(1) atoms to form GaTb6 octahedra that share corners with six equivalent Ga(1)Tb6 octahedra and edges with twelve equivalent Os(1)Tb4Ga8 cuboctahedra. The corner-sharing octahedra are not tilted. In the second Ga site, Ga(2) is bonded in a 9-coordinate geometry to three equivalent Tb(1), three equivalent Os(1), and three equivalent Ga(2) atoms. All Ga(2)-Ga(2) bond lengths are 2.67 Å.