Tb2AlGe3 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 11-coordinate geometry to two equivalent Al(1), one Ge(1), four equivalent Ge(2), and four equivalent Ge(3) atoms. In the second Tb site, Tb(2) is bonded in a 7-coordinate geometry to two equivalent Ge(2), two equivalent Ge(3), and three equivalent Ge(1) atoms. Al(1) is bonded to two equivalent Tb(1), one Ge(2), and three equivalent Ge(1) atoms to form distorted AlTb2Ge4 tetrahedra that share corners with two equivalent Ge(1)Tb4Al3 pentagonal bipyramids and edges with four equivalent Al(1)Tb2Ge4 tetrahedra. There are three inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one Tb(1), three equivalent Tb(2), and three equivalent Al(1) atoms to form distorted GeTb4Al3 pentagonal bipyramids that share corners with two equivalent Al(1)Tb2Ge4 tetrahedra and edges with six equivalent Ge(1)Tb4Al3 pentagonal bipyramids. In the second Ge site, Ge(2) is bonded in a 9-coordinate geometry to two equivalent Tb(2), four equivalent Tb(1), one Al(1), and two equivalent Ge(3) atoms. In the third Ge site, Ge(3) is bonded in a 8-coordinate geometry to two equivalent Tb(2), four equivalent Tb(1), and two equivalent Ge(2) atoms.
Tb2AlGe3 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 11-coordinate geometry to two equivalent Al(1), one Ge(1), four equivalent Ge(2), and four equivalent Ge(3) atoms. Both Tb(1)-Al(1) bond lengths are 3.37 Å. The Tb(1)-Ge(1) bond length is 3.07 Å. There are two shorter (3.02 Å) and two longer (3.12 Å) Tb(1)-Ge(2) bond lengths. There are two shorter (2.98 Å) and two longer (3.35 Å) Tb(1)-Ge(3) bond lengths. In the second Tb site, Tb(2) is bonded in a 7-coordinate geometry to two equivalent Ge(2), two equivalent Ge(3), and three equivalent Ge(1) atoms. Both Tb(2)-Ge(2) bond lengths are 3.07 Å. Both Tb(2)-Ge(3) bond lengths are 2.98 Å. There is one shorter (3.02 Å) and two longer (3.06 Å) Tb(2)-Ge(1) bond lengths. Al(1) is bonded to two equivalent Tb(1), one Ge(2), and three equivalent Ge(1) atoms to form distorted AlTb2Ge4 tetrahedra that share corners with two equivalent Ge(1)Tb4Al3 pentagonal bipyramids and edges with four equivalent Al(1)Tb2Ge4 tetrahedra. The Al(1)-Ge(2) bond length is 2.57 Å. There are two shorter (2.57 Å) and one longer (2.69 Å) Al(1)-Ge(1) bond length. There are three inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one Tb(1), three equivalent Tb(2), and three equivalent Al(1) atoms to form distorted GeTb4Al3 pentagonal bipyramids that share corners with two equivalent Al(1)Tb2Ge4 tetrahedra and edges with six equivalent Ge(1)Tb4Al3 pentagonal bipyramids. In the second Ge site, Ge(2) is bonded in a 9-coordinate geometry to two equivalent Tb(2), four equivalent Tb(1), one Al(1), and two equivalent Ge(3) atoms. There is one shorter (2.59 Å) and one longer (2.66 Å) Ge(2)-Ge(3) bond length. In the third Ge site, Ge(3) is bonded in a 8-coordinate geometry to two equivalent Tb(2), four equivalent Tb(1), and two equivalent Ge(2) atoms.