K2ZnI4 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to one I(1), one I(3), and four equivalent I(2) atoms to form distorted KI6 pentagonal pyramids that share corners with four equivalent K(2)I6 pentagonal pyramids, corners with two equivalent Zn(1)I4 tetrahedra, edges with two equivalent K(1)I6 pentagonal pyramids, edges with two equivalent Zn(1)I4 tetrahedra, and faces with two equivalent K(2)I6 pentagonal pyramids. In the second K site, K(2) is bonded to one I(1), one I(3), and four equivalent I(2) atoms to form distorted KI6 pentagonal pyramids that share corners with four equivalent K(1)I6 pentagonal pyramids, corners with four equivalent Zn(1)I4 tetrahedra, edges with two equivalent K(2)I6 pentagonal pyramids,  an edgeedge with one Zn(1)I4 tetrahedra, and faces with two equivalent K(1)I6 pentagonal pyramids. Zn(1) is bonded to one I(1), one I(3), and two equivalent I(2) atoms to form ZnI4 tetrahedra that share corners with two equivalent K(1)I6 pentagonal pyramids, corners with four equivalent K(2)I6 pentagonal pyramids,  an edgeedge with one K(2)I6 pentagonal pyramid, and edges with two equivalent K(1)I6 pentagonal pyramids. There are three inequivalent I sites. In the first I site, I(1) is bonded in a distorted T-shaped geometry to one K(1), one K(2), and one Zn(1) atom. In the second I site, I(2) is bonded to two equivalent K(1), two equivalent K(2), and one Zn(1) atom to form a mixture of distorted face, corner, and edge-sharing IK4Zn square pyramids. In the third I site, I(3) is bonded in a T-shaped geometry to one K(1), one K(2), and one Zn(1) atom.
K2ZnI4 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to one I(1), one I(3), and four equivalent I(2) atoms to form distorted KI6 pentagonal pyramids that share corners with four equivalent K(2)I6 pentagonal pyramids, corners with two equivalent Zn(1)I4 tetrahedra, edges with two equivalent K(1)I6 pentagonal pyramids, edges with two equivalent Zn(1)I4 tetrahedra, and faces with two equivalent K(2)I6 pentagonal pyramids. The K(1)-I(1) bond length is 3.58 Å. The K(1)-I(3) bond length is 3.50 Å. There are two shorter (3.60 Å) and two longer (3.66 Å) K(1)-I(2) bond lengths. In the second K site, K(2) is bonded to one I(1), one I(3), and four equivalent I(2) atoms to form distorted KI6 pentagonal pyramids that share corners with four equivalent K(1)I6 pentagonal pyramids, corners with four equivalent Zn(1)I4 tetrahedra, edges with two equivalent K(2)I6 pentagonal pyramids,  an edgeedge with one Zn(1)I4 tetrahedra, and faces with two equivalent K(1)I6 pentagonal pyramids. The K(2)-I(1) bond length is 3.63 Å. The K(2)-I(3) bond length is 3.57 Å. There are two shorter (3.64 Å) and two longer (3.67 Å) K(2)-I(2) bond lengths. Zn(1) is bonded to one I(1), one I(3), and two equivalent I(2) atoms to form ZnI4 tetrahedra that share corners with two equivalent K(1)I6 pentagonal pyramids, corners with four equivalent K(2)I6 pentagonal pyramids,  an edgeedge with one K(2)I6 pentagonal pyramid, and edges with two equivalent K(1)I6 pentagonal pyramids. The Zn(1)-I(1) bond length is 2.61 Å. The Zn(1)-I(3) bond length is 2.61 Å. Both Zn(1)-I(2) bond lengths are 2.63 Å. There are three inequivalent I sites. In the first I site, I(1) is bonded in a distorted T-shaped geometry to one K(1), one K(2), and one Zn(1) atom. In the second I site, I(2) is bonded to two equivalent K(1), two equivalent K(2), and one Zn(1) atom to form a mixture of distorted face, corner, and edge-sharing IK4Zn square pyramids. In the third I site, I(3) is bonded in a T-shaped geometry to one K(1), one K(2), and one Zn(1) atom.