Mg5Tl2 crystallizes in the triclinic P-1 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to two equivalent Mg(3), two equivalent Tl(1), and two equivalent Tl(2) atoms. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one Mg(3), two equivalent Tl(1), and two equivalent Tl(2) atoms. In the third Mg site, Mg(3) is bonded to one Mg(2), one Mg(5), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(4), two equivalent Tl(1), and two equivalent Tl(2) atoms to form a mixture of distorted corner and face-sharing MgMg8Tl4 cuboctahedra. In the fourth Mg site, Mg(4) is bonded in a 4-coordinate geometry to two equivalent Mg(3), two equivalent Tl(1), and two equivalent Tl(2) atoms. In the fifth Mg site, Mg(5) is bonded in a 4-coordinate geometry to one Mg(3), two equivalent Tl(1), and two equivalent Tl(2) atoms. There are two inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a distorted q6 geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Mg(5) atoms. In the second Tl site, Tl(2) is bonded in a distorted q6 geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Mg(5) atoms.
Mg5Tl2 crystallizes in the triclinic P-1 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to two equivalent Mg(3), two equivalent Tl(1), and two equivalent Tl(2) atoms. Both Mg(1)-Mg(3) bond lengths are 3.17 Å. There is one shorter (2.93 Å) and one longer (2.99 Å) Mg(1)-Tl(1) bond length. There is one shorter (3.18 Å) and one longer (3.19 Å) Mg(1)-Tl(2) bond length. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one Mg(3), two equivalent Tl(1), and two equivalent Tl(2) atoms. The Mg(2)-Mg(3) bond length is 3.26 Å. There is one shorter (2.95 Å) and one longer (3.07 Å) Mg(2)-Tl(1) bond length. There is one shorter (2.96 Å) and one longer (3.07 Å) Mg(2)-Tl(2) bond length. In the third Mg site, Mg(3) is bonded to one Mg(2), one Mg(5), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(4), two equivalent Tl(1), and two equivalent Tl(2) atoms to form a mixture of distorted corner and face-sharing MgMg8Tl4 cuboctahedra. The Mg(3)-Mg(5) bond length is 3.26 Å. There is one shorter (3.10 Å) and one longer (3.11 Å) Mg(3)-Mg(3) bond length. There is one shorter (3.17 Å) and one longer (3.18 Å) Mg(3)-Mg(4) bond length. There is one shorter (3.03 Å) and one longer (3.04 Å) Mg(3)-Tl(1) bond length. There is one shorter (3.02 Å) and one longer (3.04 Å) Mg(3)-Tl(2) bond length. In the fourth Mg site, Mg(4) is bonded in a 4-coordinate geometry to two equivalent Mg(3), two equivalent Tl(1), and two equivalent Tl(2) atoms. There is one shorter (3.18 Å) and one longer (3.19 Å) Mg(4)-Tl(1) bond length. There is one shorter (2.93 Å) and one longer (2.99 Å) Mg(4)-Tl(2) bond length. In the fifth Mg site, Mg(5) is bonded in a 4-coordinate geometry to one Mg(3), two equivalent Tl(1), and two equivalent Tl(2) atoms. There is one shorter (2.95 Å) and one longer (3.09 Å) Mg(5)-Tl(1) bond length. There is one shorter (2.94 Å) and one longer (3.08 Å) Mg(5)-Tl(2) bond length. There are two inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a distorted q6 geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Mg(5) atoms. In the second Tl site, Tl(2) is bonded in a distorted q6 geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Mg(5) atoms.