TmMg2 is Hexagonal Laves structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Mg sites. In the first Mg site, Mg(2) is bonded to six equivalent Mg(1) and six equivalent Tm(1) atoms to form a mixture of face, corner, and edge-sharing MgTm6Mg6 cuboctahedra. In the second Mg site, Mg(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), and six equivalent Tm(1) atoms to form a mixture of face, corner, and edge-sharing MgTm6Mg6 cuboctahedra. Tm(1) is bonded in a 16-coordinate geometry to three equivalent Mg(2), nine equivalent Mg(1), and four equivalent Tm(1) atoms.
TmMg2 is Hexagonal Laves structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Mg sites. In the first Mg site, Mg(2) is bonded to six equivalent Mg(1) and six equivalent Tm(1) atoms to form a mixture of face, corner, and edge-sharing MgTm6Mg6 cuboctahedra. All Mg(2)-Mg(1) bond lengths are 3.01 Å. All Mg(2)-Tm(1) bond lengths are 3.50 Å. In the second Mg site, Mg(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), and six equivalent Tm(1) atoms to form a mixture of face, corner, and edge-sharing MgTm6Mg6 cuboctahedra. There are two shorter (2.89 Å) and two longer (3.07 Å) Mg(1)-Mg(1) bond lengths. There are two shorter (3.48 Å) and four longer (3.49 Å) Mg(1)-Tm(1) bond lengths. Tm(1) is bonded in a 16-coordinate geometry to three equivalent Mg(2), nine equivalent Mg(1), and four equivalent Tm(1) atoms. There is one shorter (3.62 Å) and three longer (3.66 Å) Tm(1)-Tm(1) bond lengths.