Tb3Cu4Ge4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 12-coordinate geometry to six equivalent Cu(1), two equivalent Ge(1), and four equivalent Ge(2) atoms. In the second Tb site, Tb(2) is bonded to two equivalent Ge(1) and four equivalent Ge(2) atoms to form distorted edge-sharing TbGe6 octahedra. Cu(1) is bonded in a 8-coordinate geometry to three equivalent Tb(1), one Cu(1), one Ge(2), and three equivalent Ge(1) atoms. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a 9-coordinate geometry to one Tb(2), two equivalent Tb(1), and six equivalent Cu(1) atoms. In the second Ge site, Ge(2) is bonded in a 9-coordinate geometry to two equivalent Tb(2), four equivalent Tb(1), two equivalent Cu(1), and one Ge(2) atom.
Tb3Cu4Ge4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 12-coordinate geometry to six equivalent Cu(1), two equivalent Ge(1), and four equivalent Ge(2) atoms. There are four shorter (2.98 Å) and two longer (3.05 Å) Tb(1)-Cu(1) bond lengths. Both Tb(1)-Ge(1) bond lengths are 2.98 Å. All Tb(1)-Ge(2) bond lengths are 3.05 Å. In the second Tb site, Tb(2) is bonded to two equivalent Ge(1) and four equivalent Ge(2) atoms to form distorted edge-sharing TbGe6 octahedra. Both Tb(2)-Ge(1) bond lengths are 3.01 Å. All Tb(2)-Ge(2) bond lengths are 2.93 Å. Cu(1) is bonded in a 8-coordinate geometry to three equivalent Tb(1), one Cu(1), one Ge(2), and three equivalent Ge(1) atoms. The Cu(1)-Cu(1) bond length is 2.50 Å. The Cu(1)-Ge(2) bond length is 2.47 Å. There are two shorter (2.53 Å) and one longer (2.60 Å) Cu(1)-Ge(1) bond length. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a 9-coordinate geometry to one Tb(2), two equivalent Tb(1), and six equivalent Cu(1) atoms. In the second Ge site, Ge(2) is bonded in a 9-coordinate geometry to two equivalent Tb(2), four equivalent Tb(1), two equivalent Cu(1), and one Ge(2) atom. The Ge(2)-Ge(2) bond length is 2.52 Å.