Tm2Fe15Ga2 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 18-coordinate geometry to six equivalent Fe(2) and twelve equivalent Fe(3) atoms. In the second Tm site, Tm(2) is bonded in a 20-coordinate geometry to six equivalent Fe(1), six equivalent Fe(2), six equivalent Fe(3), and two equivalent Ga(1) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent Tm(2), four equivalent Fe(2), four equivalent Fe(3), and two equivalent Ga(1) atoms to form FeTm2Ga2Fe8 cuboctahedra that share corners with four equivalent Fe(1)Tm2Ga2Fe8 cuboctahedra, corners with ten equivalent Fe(3)Tm3GaFe8 cuboctahedra, edges with six equivalent Fe(3)Tm3GaFe8 cuboctahedra, faces with four equivalent Fe(3)Tm3GaFe8 cuboctahedra, and faces with six equivalent Fe(1)Tm2Ga2Fe8 cuboctahedra. In the second Fe site, Fe(2) is bonded in a 12-coordinate geometry to one Tm(1), one Tm(2), two equivalent Fe(1), two equivalent Fe(2), four equivalent Fe(3), and two equivalent Ga(1) atoms. In the third Fe site, Fe(3) is bonded to one Tm(2), two equivalent Tm(1), two equivalent Fe(1), two equivalent Fe(3), four equivalent Fe(2), and one Ga(1) atom to form FeTm3GaFe8 cuboctahedra that share corners with five equivalent Fe(1)Tm2Ga2Fe8 cuboctahedra, corners with ten equivalent Fe(3)Tm3GaFe8 cuboctahedra, edges with three equivalent Fe(1)Tm2Ga2Fe8 cuboctahedra, edges with five equivalent Fe(3)Tm3GaFe8 cuboctahedra, faces with two equivalent Fe(1)Tm2Ga2Fe8 cuboctahedra, and faces with eight equivalent Fe(3)Tm3GaFe8 cuboctahedra. Ga(1) is bonded in a 14-coordinate geometry to one Tm(2), three equivalent Fe(1), three equivalent Fe(3), six equivalent Fe(2), and one Ga(1) atom.
Tm2Fe15Ga2 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 18-coordinate geometry to six equivalent Fe(2) and twelve equivalent Fe(3) atoms. All Tm(1)-Fe(2) bond lengths are 2.95 Å. There are six shorter (3.14 Å) and six longer (3.27 Å) Tm(1)-Fe(3) bond lengths. In the second Tm site, Tm(2) is bonded in a 20-coordinate geometry to six equivalent Fe(1), six equivalent Fe(2), six equivalent Fe(3), and two equivalent Ga(1) atoms. All Tm(2)-Fe(1) bond lengths are 3.22 Å. All Tm(2)-Fe(2) bond lengths are 2.99 Å. All Tm(2)-Fe(3) bond lengths are 3.18 Å. Both Tm(2)-Ga(1) bond lengths are 2.90 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent Tm(2), four equivalent Fe(2), four equivalent Fe(3), and two equivalent Ga(1) atoms to form FeTm2Ga2Fe8 cuboctahedra that share corners with four equivalent Fe(1)Tm2Ga2Fe8 cuboctahedra, corners with ten equivalent Fe(3)Tm3GaFe8 cuboctahedra, edges with six equivalent Fe(3)Tm3GaFe8 cuboctahedra, faces with four equivalent Fe(3)Tm3GaFe8 cuboctahedra, and faces with six equivalent Fe(1)Tm2Ga2Fe8 cuboctahedra. All Fe(1)-Fe(2) bond lengths are 2.48 Å. All Fe(1)-Fe(3) bond lengths are 2.47 Å. Both Fe(1)-Ga(1) bond lengths are 2.59 Å. In the second Fe site, Fe(2) is bonded in a 12-coordinate geometry to one Tm(1), one Tm(2), two equivalent Fe(1), two equivalent Fe(2), four equivalent Fe(3), and two equivalent Ga(1) atoms. There is one shorter (2.55 Å) and one longer (2.64 Å) Fe(2)-Fe(2) bond length. There are two shorter (2.54 Å) and two longer (2.59 Å) Fe(2)-Fe(3) bond lengths. Both Fe(2)-Ga(1) bond lengths are 2.89 Å. In the third Fe site, Fe(3) is bonded to one Tm(2), two equivalent Tm(1), two equivalent Fe(1), two equivalent Fe(3), four equivalent Fe(2), and one Ga(1) atom to form FeTm3GaFe8 cuboctahedra that share corners with five equivalent Fe(1)Tm2Ga2Fe8 cuboctahedra, corners with ten equivalent Fe(3)Tm3GaFe8 cuboctahedra, edges with three equivalent Fe(1)Tm2Ga2Fe8 cuboctahedra, edges with five equivalent Fe(3)Tm3GaFe8 cuboctahedra, faces with two equivalent Fe(1)Tm2Ga2Fe8 cuboctahedra, and faces with eight equivalent Fe(3)Tm3GaFe8 cuboctahedra. Both Fe(3)-Fe(3) bond lengths are 2.44 Å. The Fe(3)-Ga(1) bond length is 2.65 Å. Ga(1) is bonded in a 14-coordinate geometry to one Tm(2), three equivalent Fe(1), three equivalent Fe(3), six equivalent Fe(2), and one Ga(1) atom. The Ga(1)-Ga(1) bond length is 2.52 Å.