ZnFeO2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(2), two equivalent O(1), and three equivalent O(3) atoms. In the second Fe site, Fe(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form FeO6 octahedra that share corners with four equivalent Zn(1)O5 square pyramids, edges with four equivalent Fe(2)O6 octahedra, and  a faceface with one Zn(1)O5 square pyramid. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form ZnO5 square pyramids that share corners with four equivalent Fe(2)O6 octahedra, edges with two equivalent Zn(1)O5 square pyramids, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-52°. In the second Zn site, Zn(2) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), and two equivalent O(2) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Fe(2), two equivalent Fe(1), and one Zn(1) atom to form distorted OZnFe3 trigonal pyramids that share corners with two equivalent O(3)Zn3Fe3 octahedra, corners with four equivalent O(2)Zn2Fe3 trigonal bipyramids, corners with two equivalent O(1)ZnFe3 trigonal pyramids, and edges with three equivalent O(3)Zn3Fe3 octahedra. The corner-sharing octahedral tilt angles are 19°. In the second O site, O(2) is bonded to one Fe(1), two equivalent Fe(2), and two equivalent Zn(2) atoms to form distorted OZn2Fe3 trigonal bipyramids that share  a cornercorner with one O(3)Zn3Fe3 octahedra, corners with four equivalent O(1)ZnFe3 trigonal pyramids, edges with two equivalent O(3)Zn3Fe3 octahedra, and edges with two equivalent O(2)Zn2Fe3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 16°. In the third O site, O(3) is bonded to three equivalent Fe(1), one Zn(2), and two equivalent Zn(1) atoms to form distorted OZn3Fe3 octahedra that share  a cornercorner with one O(2)Zn2Fe3 trigonal bipyramid, corners with two equivalent O(1)ZnFe3 trigonal pyramids, edges with four equivalent O(3)Zn3Fe3 octahedra, edges with two equivalent O(2)Zn2Fe3 trigonal bipyramids, and edges with three equivalent O(1)ZnFe3 trigonal pyramids. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to three equivalent Fe(2), one Zn(2), and two equivalent Zn(1) atoms.
ZnFeO2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(2), two equivalent O(1), and three equivalent O(3) atoms. The Fe(1)-O(2) bond length is 1.98 Å. Both Fe(1)-O(1) bond lengths are 1.97 Å. There are two shorter (2.11 Å) and one longer (2.60 Å) Fe(1)-O(3) bond length. In the second Fe site, Fe(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form FeO6 octahedra that share corners with four equivalent Zn(1)O5 square pyramids, edges with four equivalent Fe(2)O6 octahedra, and  a faceface with one Zn(1)O5 square pyramid. The Fe(2)-O(1) bond length is 2.10 Å. Both Fe(2)-O(2) bond lengths are 2.25 Å. There is one shorter (2.10 Å) and two longer (2.30 Å) Fe(2)-O(4) bond lengths. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form ZnO5 square pyramids that share corners with four equivalent Fe(2)O6 octahedra, edges with two equivalent Zn(1)O5 square pyramids, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-52°. The Zn(1)-O(1) bond length is 2.13 Å. Both Zn(1)-O(3) bond lengths are 2.17 Å. Both Zn(1)-O(4) bond lengths are 2.10 Å. In the second Zn site, Zn(2) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), and two equivalent O(2) atoms. The Zn(2)-O(3) bond length is 2.28 Å. The Zn(2)-O(4) bond length is 2.40 Å. Both Zn(2)-O(2) bond lengths are 2.11 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Fe(2), two equivalent Fe(1), and one Zn(1) atom to form distorted OZnFe3 trigonal pyramids that share corners with two equivalent O(3)Zn3Fe3 octahedra, corners with four equivalent O(2)Zn2Fe3 trigonal bipyramids, corners with two equivalent O(1)ZnFe3 trigonal pyramids, and edges with three equivalent O(3)Zn3Fe3 octahedra. The corner-sharing octahedral tilt angles are 19°. In the second O site, O(2) is bonded to one Fe(1), two equivalent Fe(2), and two equivalent Zn(2) atoms to form distorted OZn2Fe3 trigonal bipyramids that share  a cornercorner with one O(3)Zn3Fe3 octahedra, corners with four equivalent O(1)ZnFe3 trigonal pyramids, edges with two equivalent O(3)Zn3Fe3 octahedra, and edges with two equivalent O(2)Zn2Fe3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 16°. In the third O site, O(3) is bonded to three equivalent Fe(1), one Zn(2), and two equivalent Zn(1) atoms to form distorted OZn3Fe3 octahedra that share  a cornercorner with one O(2)Zn2Fe3 trigonal bipyramid, corners with two equivalent O(1)ZnFe3 trigonal pyramids, edges with four equivalent O(3)Zn3Fe3 octahedra, edges with two equivalent O(2)Zn2Fe3 trigonal bipyramids, and edges with three equivalent O(1)ZnFe3 trigonal pyramids. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to three equivalent Fe(2), one Zn(2), and two equivalent Zn(1) atoms.