Mg2ZnAs2 crystallizes in the trigonal P3m1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent As(1) and three equivalent As(2) atoms to form MgAs6 octahedra that share corners with six equivalent Mg(2)Zn3As4 tetrahedra, edges with six equivalent Mg(1)As6 octahedra, and edges with three equivalent Mg(2)Zn3As4 tetrahedra. In the second Mg site, Mg(2) is bonded to three equivalent Zn(1), one As(1), and three equivalent As(2) atoms to form distorted MgZn3As4 tetrahedra that share corners with six equivalent Mg(1)As6 octahedra, corners with six equivalent As(1)Mg4Zn3 pentagonal bipyramids, edges with three equivalent Mg(1)As6 octahedra, edges with six equivalent Mg(2)Zn3As4 tetrahedra, and  a faceface with one As(1)Mg4Zn3 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 11-56°. Zn(1) is bonded in a 7-coordinate geometry to three equivalent Mg(2), one As(2), and three equivalent As(1) atoms. There are two inequivalent As sites. In the first As site, As(1) is bonded to one Mg(2), three equivalent Mg(1), and three equivalent Zn(1) atoms to form distorted AsMg4Zn3 pentagonal bipyramids that share corners with six equivalent Mg(2)Zn3As4 tetrahedra, edges with six equivalent As(1)Mg4Zn3 pentagonal bipyramids, and  a faceface with one Mg(2)Zn3As4 tetrahedra. In the second As site, As(2) is bonded in a 7-coordinate geometry to three equivalent Mg(1), three equivalent Mg(2), and one Zn(1) atom.
Mg2ZnAs2 crystallizes in the trigonal P3m1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent As(1) and three equivalent As(2) atoms to form MgAs6 octahedra that share corners with six equivalent Mg(2)Zn3As4 tetrahedra, edges with six equivalent Mg(1)As6 octahedra, and edges with three equivalent Mg(2)Zn3As4 tetrahedra. All Mg(1)-As(1) bond lengths are 2.90 Å. All Mg(1)-As(2) bond lengths are 2.83 Å. In the second Mg site, Mg(2) is bonded to three equivalent Zn(1), one As(1), and three equivalent As(2) atoms to form distorted MgZn3As4 tetrahedra that share corners with six equivalent Mg(1)As6 octahedra, corners with six equivalent As(1)Mg4Zn3 pentagonal bipyramids, edges with three equivalent Mg(1)As6 octahedra, edges with six equivalent Mg(2)Zn3As4 tetrahedra, and  a faceface with one As(1)Mg4Zn3 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 11-56°. All Mg(2)-Zn(1) bond lengths are 2.97 Å. The Mg(2)-As(1) bond length is 2.64 Å. All Mg(2)-As(2) bond lengths are 2.57 Å. Zn(1) is bonded in a 7-coordinate geometry to three equivalent Mg(2), one As(2), and three equivalent As(1) atoms. The Zn(1)-As(2) bond length is 2.70 Å. All Zn(1)-As(1) bond lengths are 2.55 Å. There are two inequivalent As sites. In the first As site, As(1) is bonded to one Mg(2), three equivalent Mg(1), and three equivalent Zn(1) atoms to form distorted AsMg4Zn3 pentagonal bipyramids that share corners with six equivalent Mg(2)Zn3As4 tetrahedra, edges with six equivalent As(1)Mg4Zn3 pentagonal bipyramids, and  a faceface with one Mg(2)Zn3As4 tetrahedra. In the second As site, As(2) is bonded in a 7-coordinate geometry to three equivalent Mg(1), three equivalent Mg(2), and one Zn(1) atom.