Sr2Zn2As3 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one As(2), two equivalent As(1), and three equivalent As(3) atoms to form distorted SrAs6 octahedra that share corners with three equivalent Zn(1)Sr2As4 tetrahedra, corners with four equivalent Zn(2)SrAs4 tetrahedra, edges with four equivalent Sr(1)As6 octahedra, edges with two equivalent Zn(2)SrAs4 tetrahedra, and edges with three equivalent Zn(1)Sr2As4 tetrahedra. In the second Sr site, Sr(2) is bonded in a 10-coordinate geometry to one Zn(2), two equivalent Zn(1), three equivalent As(2), and four equivalent As(1) atoms. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to two equivalent Sr(2), one As(1), one As(2), and two equivalent As(3) atoms to form distorted ZnSr2As4 tetrahedra that share corners with three equivalent Sr(1)As6 octahedra, corners with two equivalent Zn(2)SrAs4 tetrahedra, edges with three equivalent Sr(1)As6 octahedra, edges with two equivalent Zn(1)Sr2As4 tetrahedra, and faces with two equivalent Zn(2)SrAs4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-49°. In the second Zn site, Zn(2) is bonded to one Sr(2), two equivalent As(2), and two equivalent As(3) atoms to form distorted ZnSrAs4 tetrahedra that share corners with four equivalent Sr(1)As6 octahedra, corners with two equivalent Zn(1)Sr2As4 tetrahedra, corners with two equivalent Zn(2)SrAs4 tetrahedra, edges with two equivalent Sr(1)As6 octahedra,  an edgeedge with one Zn(2)SrAs4 tetrahedra, and faces with two equivalent Zn(1)Sr2As4 tetrahedra. The corner-sharing octahedral tilt angles range from 26-55°. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to two equivalent Sr(1), four equivalent Sr(2), one Zn(1), and one As(1) atom. In the second As site, As(2) is bonded in a 7-coordinate geometry to one Sr(1), three equivalent Sr(2), one Zn(1), and two equivalent Zn(2) atoms. In the third As site, As(3) is bonded in a 7-coordinate geometry to three equivalent Sr(1), two equivalent Zn(1), and two equivalent Zn(2) atoms.
Sr2Zn2As3 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one As(2), two equivalent As(1), and three equivalent As(3) atoms to form distorted SrAs6 octahedra that share corners with three equivalent Zn(1)Sr2As4 tetrahedra, corners with four equivalent Zn(2)SrAs4 tetrahedra, edges with four equivalent Sr(1)As6 octahedra, edges with two equivalent Zn(2)SrAs4 tetrahedra, and edges with three equivalent Zn(1)Sr2As4 tetrahedra. The Sr(1)-As(2) bond length is 3.09 Å. Both Sr(1)-As(1) bond lengths are 3.15 Å. There is one shorter (3.11 Å) and two longer (3.13 Å) Sr(1)-As(3) bond lengths. In the second Sr site, Sr(2) is bonded in a 10-coordinate geometry to one Zn(2), two equivalent Zn(1), three equivalent As(2), and four equivalent As(1) atoms. The Sr(2)-Zn(2) bond length is 3.42 Å. Both Sr(2)-Zn(1) bond lengths are 3.36 Å. There are two shorter (3.18 Å) and one longer (3.27 Å) Sr(2)-As(2) bond length. There are two shorter (3.24 Å) and two longer (3.31 Å) Sr(2)-As(1) bond lengths. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to two equivalent Sr(2), one As(1), one As(2), and two equivalent As(3) atoms to form distorted ZnSr2As4 tetrahedra that share corners with three equivalent Sr(1)As6 octahedra, corners with two equivalent Zn(2)SrAs4 tetrahedra, edges with three equivalent Sr(1)As6 octahedra, edges with two equivalent Zn(1)Sr2As4 tetrahedra, and faces with two equivalent Zn(2)SrAs4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-49°. The Zn(1)-As(1) bond length is 2.65 Å. The Zn(1)-As(2) bond length is 2.53 Å. Both Zn(1)-As(3) bond lengths are 2.55 Å. In the second Zn site, Zn(2) is bonded to one Sr(2), two equivalent As(2), and two equivalent As(3) atoms to form distorted ZnSrAs4 tetrahedra that share corners with four equivalent Sr(1)As6 octahedra, corners with two equivalent Zn(1)Sr2As4 tetrahedra, corners with two equivalent Zn(2)SrAs4 tetrahedra, edges with two equivalent Sr(1)As6 octahedra,  an edgeedge with one Zn(2)SrAs4 tetrahedra, and faces with two equivalent Zn(1)Sr2As4 tetrahedra. The corner-sharing octahedral tilt angles range from 26-55°. Both Zn(2)-As(2) bond lengths are 2.56 Å. There is one shorter (2.53 Å) and one longer (2.66 Å) Zn(2)-As(3) bond length. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to two equivalent Sr(1), four equivalent Sr(2), one Zn(1), and one As(1) atom. The As(1)-As(1) bond length is 2.51 Å. In the second As site, As(2) is bonded in a 7-coordinate geometry to one Sr(1), three equivalent Sr(2), one Zn(1), and two equivalent Zn(2) atoms. In the third As site, As(3) is bonded in a 7-coordinate geometry to three equivalent Sr(1), two equivalent Zn(1), and two equivalent Zn(2) atoms.