Ba3Zn2As4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to three equivalent Zn(1), three equivalent As(1), and four equivalent As(2) atoms. In the second Ba site, Ba(2) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form BaAs6 octahedra that share corners with two equivalent Zn(1)Ba3As4 tetrahedra, edges with two equivalent Ba(2)As6 octahedra, and edges with four equivalent Zn(1)Ba3As4 tetrahedra. Zn(1) is bonded to three equivalent Ba(1), one As(2), and three equivalent As(1) atoms to form distorted ZnBa3As4 tetrahedra that share  a cornercorner with one Ba(2)As6 octahedra, edges with two equivalent Ba(2)As6 octahedra, edges with two equivalent Zn(1)Ba3As4 tetrahedra, and faces with two equivalent Zn(1)Ba3As4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There are two inequivalent As sites. In the first As site, As(1) is bonded in a 7-coordinate geometry to one Ba(2), three equivalent Ba(1), and three equivalent Zn(1) atoms. In the second As site, As(2) is bonded in a 8-coordinate geometry to two equivalent Ba(2), four equivalent Ba(1), one Zn(1), and one As(2) atom.
Ba3Zn2As4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to three equivalent Zn(1), three equivalent As(1), and four equivalent As(2) atoms. There are two shorter (3.44 Å) and one longer (3.55 Å) Ba(1)-Zn(1) bond length. There are two shorter (3.36 Å) and one longer (3.62 Å) Ba(1)-As(1) bond length. There are two shorter (3.43 Å) and two longer (3.44 Å) Ba(1)-As(2) bond lengths. In the second Ba site, Ba(2) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form BaAs6 octahedra that share corners with two equivalent Zn(1)Ba3As4 tetrahedra, edges with two equivalent Ba(2)As6 octahedra, and edges with four equivalent Zn(1)Ba3As4 tetrahedra. Both Ba(2)-As(1) bond lengths are 3.23 Å. All Ba(2)-As(2) bond lengths are 3.30 Å. Zn(1) is bonded to three equivalent Ba(1), one As(2), and three equivalent As(1) atoms to form distorted ZnBa3As4 tetrahedra that share  a cornercorner with one Ba(2)As6 octahedra, edges with two equivalent Ba(2)As6 octahedra, edges with two equivalent Zn(1)Ba3As4 tetrahedra, and faces with two equivalent Zn(1)Ba3As4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. The Zn(1)-As(2) bond length is 2.67 Å. There is one shorter (2.58 Å) and two longer (2.62 Å) Zn(1)-As(1) bond lengths. There are two inequivalent As sites. In the first As site, As(1) is bonded in a 7-coordinate geometry to one Ba(2), three equivalent Ba(1), and three equivalent Zn(1) atoms. In the second As site, As(2) is bonded in a 8-coordinate geometry to two equivalent Ba(2), four equivalent Ba(1), one Zn(1), and one As(2) atom. The As(2)-As(2) bond length is 2.49 Å.