MgZn2 crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Zn(3), two equivalent Zn(1), two equivalent Zn(4), and three equivalent Zn(2) atoms to form distorted MgZn8 cuboctahedra that share corners with four equivalent Mg(1)Zn8 cuboctahedra, corners with six equivalent Mg(2)Zn8 cuboctahedra, corners with six equivalent Zn(4)Mg4Zn8 cuboctahedra, edges with three equivalent Mg(2)Zn8 cuboctahedra,  a faceface with one Mg(2)Zn8 cuboctahedra, faces with two equivalent Mg(1)Zn8 cuboctahedra, and faces with three equivalent Zn(4)Mg4Zn8 cuboctahedra. In the second Mg site, Mg(2) is bonded to one Zn(1), two equivalent Zn(2), two equivalent Zn(4), and three equivalent Zn(3) atoms to form distorted MgZn8 cuboctahedra that share corners with four equivalent Mg(2)Zn8 cuboctahedra, corners with six equivalent Mg(1)Zn8 cuboctahedra, corners with six equivalent Zn(4)Mg4Zn8 cuboctahedra, edges with three equivalent Mg(1)Zn8 cuboctahedra,  a faceface with one Mg(1)Zn8 cuboctahedra, faces with two equivalent Mg(2)Zn8 cuboctahedra, and faces with three equivalent Zn(4)Mg4Zn8 cuboctahedra. There are four inequivalent Zn sites. In the first Zn site, Zn(1) is bonded in a 3-coordinate geometry to one Mg(2), two equivalent Mg(1), two equivalent Zn(2), two equivalent Zn(3), and three equivalent Zn(4) atoms. In the second Zn site, Zn(2) is bonded in a 12-coordinate geometry to two equivalent Mg(2), three equivalent Mg(1), one Zn(4), two equivalent Zn(1), two equivalent Zn(2), and two equivalent Zn(3) atoms. In the third Zn site, Zn(3) is bonded in a 12-coordinate geometry to one Mg(1), three equivalent Mg(2), two equivalent Zn(1), two equivalent Zn(2), two equivalent Zn(3), and two equivalent Zn(4) atoms. In the fourth Zn site, Zn(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), one Zn(2), two equivalent Zn(3), two equivalent Zn(4), and three equivalent Zn(1) atoms to form distorted ZnMg4Zn8 cuboctahedra that share corners with six equivalent Mg(1)Zn8 cuboctahedra, corners with six equivalent Mg(2)Zn8 cuboctahedra, corners with six equivalent Zn(4)Mg4Zn8 cuboctahedra, faces with two equivalent Zn(4)Mg4Zn8 cuboctahedra, faces with three equivalent Mg(1)Zn8 cuboctahedra, and faces with three equivalent Mg(2)Zn8 cuboctahedra.
MgZn2 crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Zn(3), two equivalent Zn(1), two equivalent Zn(4), and three equivalent Zn(2) atoms to form distorted MgZn8 cuboctahedra that share corners with four equivalent Mg(1)Zn8 cuboctahedra, corners with six equivalent Mg(2)Zn8 cuboctahedra, corners with six equivalent Zn(4)Mg4Zn8 cuboctahedra, edges with three equivalent Mg(2)Zn8 cuboctahedra,  a faceface with one Mg(2)Zn8 cuboctahedra, faces with two equivalent Mg(1)Zn8 cuboctahedra, and faces with three equivalent Zn(4)Mg4Zn8 cuboctahedra. The Mg(1)-Zn(3) bond length is 2.88 Å. Both Mg(1)-Zn(1) bond lengths are 2.83 Å. Both Mg(1)-Zn(4) bond lengths are 2.87 Å. There are two shorter (2.82 Å) and one longer (2.86 Å) Mg(1)-Zn(2) bond length. In the second Mg site, Mg(2) is bonded to one Zn(1), two equivalent Zn(2), two equivalent Zn(4), and three equivalent Zn(3) atoms to form distorted MgZn8 cuboctahedra that share corners with four equivalent Mg(2)Zn8 cuboctahedra, corners with six equivalent Mg(1)Zn8 cuboctahedra, corners with six equivalent Zn(4)Mg4Zn8 cuboctahedra, edges with three equivalent Mg(1)Zn8 cuboctahedra,  a faceface with one Mg(1)Zn8 cuboctahedra, faces with two equivalent Mg(2)Zn8 cuboctahedra, and faces with three equivalent Zn(4)Mg4Zn8 cuboctahedra. The Mg(2)-Zn(1) bond length is 2.77 Å. Both Mg(2)-Zn(2) bond lengths are 2.85 Å. Both Mg(2)-Zn(4) bond lengths are 2.93 Å. There is one shorter (2.78 Å) and two longer (2.88 Å) Mg(2)-Zn(3) bond lengths. There are four inequivalent Zn sites. In the first Zn site, Zn(1) is bonded in a 3-coordinate geometry to one Mg(2), two equivalent Mg(1), two equivalent Zn(2), two equivalent Zn(3), and three equivalent Zn(4) atoms. Both Zn(1)-Zn(2) bond lengths are 2.91 Å. Both Zn(1)-Zn(3) bond lengths are 2.96 Å. There are two shorter (2.82 Å) and one longer (2.85 Å) Zn(1)-Zn(4) bond length. In the second Zn site, Zn(2) is bonded in a 12-coordinate geometry to two equivalent Mg(2), three equivalent Mg(1), one Zn(4), two equivalent Zn(1), two equivalent Zn(2), and two equivalent Zn(3) atoms. The Zn(2)-Zn(4) bond length is 2.78 Å. Both Zn(2)-Zn(2) bond lengths are 3.04 Å. Both Zn(2)-Zn(3) bond lengths are 3.02 Å. In the third Zn site, Zn(3) is bonded in a 12-coordinate geometry to one Mg(1), three equivalent Mg(2), two equivalent Zn(1), two equivalent Zn(2), two equivalent Zn(3), and two equivalent Zn(4) atoms. Both Zn(3)-Zn(3) bond lengths are 3.04 Å. Both Zn(3)-Zn(4) bond lengths are 2.81 Å. In the fourth Zn site, Zn(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), one Zn(2), two equivalent Zn(3), two equivalent Zn(4), and three equivalent Zn(1) atoms to form distorted ZnMg4Zn8 cuboctahedra that share corners with six equivalent Mg(1)Zn8 cuboctahedra, corners with six equivalent Mg(2)Zn8 cuboctahedra, corners with six equivalent Zn(4)Mg4Zn8 cuboctahedra, faces with two equivalent Zn(4)Mg4Zn8 cuboctahedra, faces with three equivalent Mg(1)Zn8 cuboctahedra, and faces with three equivalent Mg(2)Zn8 cuboctahedra. Both Zn(4)-Zn(4) bond lengths are 3.04 Å.