Tb2FeGa8 crystallizes in the tetragonal P4/mmm space group. Tb(1) is bonded to four equivalent Ga(1), four equivalent Ga(2), and four equivalent Ga(3) atoms to form a mixture of face and corner-sharing TbGa12 cuboctahedra. Fe(1) is bonded in a body-centered cubic geometry to eight equivalent Ga(1) atoms. There are three inequivalent Ga sites. In the first Ga site, Ga(1) is bonded in a 11-coordinate geometry to two equivalent Tb(1), two equivalent Fe(1), two equivalent Ga(3), and five equivalent Ga(1) atoms. In the second Ga site, Ga(2) is bonded in a distorted square co-planar geometry to four equivalent Tb(1) atoms. In the third Ga site, Ga(3) is bonded in a distorted rectangular see-saw-like geometry to four equivalent Tb(1) and four equivalent Ga(1) atoms.
Tb2FeGa8 crystallizes in the tetragonal P4/mmm space group. Tb(1) is bonded to four equivalent Ga(1), four equivalent Ga(2), and four equivalent Ga(3) atoms to form a mixture of face and corner-sharing TbGa12 cuboctahedra. All Tb(1)-Ga(1) bond lengths are 3.00 Å. All Tb(1)-Ga(2) bond lengths are 3.06 Å. All Tb(1)-Ga(3) bond lengths are 3.02 Å. Fe(1) is bonded in a body-centered cubic geometry to eight equivalent Ga(1) atoms. All Fe(1)-Ga(1) bond lengths are 2.48 Å. There are three inequivalent Ga sites. In the first Ga site, Ga(1) is bonded in a 11-coordinate geometry to two equivalent Tb(1), two equivalent Fe(1), two equivalent Ga(3), and five equivalent Ga(1) atoms. Both Ga(1)-Ga(3) bond lengths are 2.99 Å. There is one shorter (2.54 Å) and four longer (3.02 Å) Ga(1)-Ga(1) bond lengths. In the second Ga site, Ga(2) is bonded in a distorted square co-planar geometry to four equivalent Tb(1) atoms. In the third Ga site, Ga(3) is bonded in a distorted rectangular see-saw-like geometry to four equivalent Tb(1) and four equivalent Ga(1) atoms.