Tm3(FeGe)4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded to two equivalent Ge(1) and four equivalent Ge(2) atoms to form distorted edge-sharing TmGe6 octahedra. In the second Tm site, Tm(2) is bonded in a 12-coordinate geometry to six equivalent Fe(1), two equivalent Ge(1), and four equivalent Ge(2) atoms. Fe(1) is bonded in a 8-coordinate geometry to three equivalent Tm(2), one Fe(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 Tm(1), two equivalent Tm(2), and six equivalent Fe(1) atoms. In the second Ge site, Ge(2) is bonded in a 9-coordinate geometry to two equivalent Tm(1), four equivalent Tm(2), two equivalent Fe(1), and one Ge(2) atom.
Tm3(FeGe)4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded to two equivalent Ge(1) and four equivalent Ge(2) atoms to form distorted edge-sharing TmGe6 octahedra. Both Tm(1)-Ge(1) bond lengths are 2.97 Å. All Tm(1)-Ge(2) bond lengths are 2.91 Å. In the second Tm site, Tm(2) is bonded in a 12-coordinate geometry to six equivalent Fe(1), two equivalent Ge(1), and four equivalent Ge(2) atoms. There are two shorter (2.91 Å) and four longer (3.06 Å) Tm(2)-Fe(1) bond lengths. Both Tm(2)-Ge(1) bond lengths are 2.89 Å. All Tm(2)-Ge(2) bond lengths are 2.99 Å. Fe(1) is bonded in a 8-coordinate geometry to three equivalent Tm(2), one Fe(1), one Ge(2), and three equivalent Ge(1) atoms. The Fe(1)-Fe(1) bond length is 2.46 Å. The Fe(1)-Ge(2) bond length is 2.50 Å. There are two shorter (2.48 Å) and one longer (2.55 Å) Fe(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 Tm(1), two equivalent Tm(2), and six equivalent Fe(1) atoms. In the second Ge site, Ge(2) is bonded in a 9-coordinate geometry to two equivalent Tm(1), four equivalent Tm(2), two equivalent Fe(1), and one Ge(2) atom. The Ge(2)-Ge(2) bond length is 2.67 Å.