Cr4ZnO8 crystallizes in the monoclinic Cm space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(7), two equivalent O(4), and two equivalent O(5) atoms to form CrO6 octahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(4)O6 octahedra, and edges with two equivalent Zn(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 48-52°. In the second Cr site, Cr(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form distorted CrO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra, corners with two equivalent Zn(1)O5 square pyramids, edges with two equivalent Cr(2)O6 octahedra, edges with two equivalent Cr(3)O6 octahedra, and  a faceface with one Zn(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 48-55°. In the third Cr site, Cr(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form CrO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra, corners with two equivalent Zn(1)O5 square pyramids, edges with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Cr(3)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. In the fourth Cr site, Cr(4) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, corners with two equivalent Zn(1)O5 square pyramids, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(4)O6 octahedra, and  an edgeedge with one Zn(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 52-55°. Zn(1) is bonded to one O(4), two equivalent O(6), and two equivalent O(7) atoms to form ZnO5 square pyramids that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra,  an edgeedge with one Cr(4)O6 octahedra, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Zn(1)O5 square pyramids, and  a faceface with one Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-56°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Cr(3) and two equivalent Cr(4) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Cr(1) and two equivalent Cr(3) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Cr(4) and two equivalent Cr(2) atoms. In the fourth O site, O(4) is bonded to one Cr(2), two equivalent Cr(1), and one Zn(1) atom to form OZnCr3 trigonal pyramids that share corners with two equivalent O(4)ZnCr3 trigonal pyramids, edges with two equivalent O(7)Zn2Cr3 square pyramids, and edges with two equivalent O(6)Zn2Cr3 trigonal bipyramids. In the fifth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Cr(4) and two equivalent Cr(1) atoms. In the sixth O site, O(6) is bonded to one Cr(3), two equivalent Cr(2), and two equivalent Zn(1) atoms to form distorted OZn2Cr3 trigonal bipyramids that share corners with two equivalent O(7)Zn2Cr3 square pyramids,  an edgeedge with one O(7)Zn2Cr3 square pyramid, edges with two equivalent O(6)Zn2Cr3 trigonal bipyramids, and edges with two equivalent O(4)ZnCr3 trigonal pyramids. In the seventh O site, O(7) is bonded to one Cr(1), two equivalent Cr(4), and two equivalent Zn(1) atoms to form OZn2Cr3 square pyramids that share corners with two equivalent O(6)Zn2Cr3 trigonal bipyramids, edges with two equivalent O(7)Zn2Cr3 square pyramids,  an edgeedge with one O(6)Zn2Cr3 trigonal bipyramid, and edges with two equivalent O(4)ZnCr3 trigonal pyramids. In the eighth O site, O(8) is bonded in a trigonal non-coplanar geometry to one Cr(2) and two equivalent Cr(3) atoms.
Cr4ZnO8 crystallizes in the monoclinic Cm space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(7), two equivalent O(4), and two equivalent O(5) atoms to form CrO6 octahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(4)O6 octahedra, and edges with two equivalent Zn(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 48-52°. The Cr(1)-O(2) bond length is 1.92 Å. The Cr(1)-O(7) bond length is 2.15 Å. Both Cr(1)-O(4) bond lengths are 2.01 Å. Both Cr(1)-O(5) bond lengths are 1.95 Å. In the second Cr site, Cr(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form distorted CrO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra, corners with two equivalent Zn(1)O5 square pyramids, edges with two equivalent Cr(2)O6 octahedra, edges with two equivalent Cr(3)O6 octahedra, and  a faceface with one Zn(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 48-55°. The Cr(2)-O(4) bond length is 1.94 Å. The Cr(2)-O(8) bond length is 1.89 Å. Both Cr(2)-O(3) bond lengths are 1.91 Å. Both Cr(2)-O(6) bond lengths are 2.19 Å. In the third Cr site, Cr(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form CrO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra, corners with two equivalent Zn(1)O5 square pyramids, edges with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Cr(3)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. The Cr(3)-O(1) bond length is 1.92 Å. The Cr(3)-O(6) bond length is 2.06 Å. Both Cr(3)-O(2) bond lengths are 1.96 Å. Both Cr(3)-O(8) bond lengths are 1.98 Å. In the fourth Cr site, Cr(4) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, corners with two equivalent Zn(1)O5 square pyramids, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(4)O6 octahedra, and  an edgeedge with one Zn(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 52-55°. The Cr(4)-O(3) bond length is 1.98 Å. The Cr(4)-O(5) bond length is 1.96 Å. Both Cr(4)-O(1) bond lengths are 1.92 Å. Both Cr(4)-O(7) bond lengths are 2.12 Å. Zn(1) is bonded to one O(4), two equivalent O(6), and two equivalent O(7) atoms to form ZnO5 square pyramids that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra,  an edgeedge with one Cr(4)O6 octahedra, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Zn(1)O5 square pyramids, and  a faceface with one Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-56°. The Zn(1)-O(4) bond length is 2.16 Å. Both Zn(1)-O(6) bond lengths are 2.10 Å. Both Zn(1)-O(7) bond lengths are 2.09 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Cr(3) and two equivalent Cr(4) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Cr(1) and two equivalent Cr(3) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Cr(4) and two equivalent Cr(2) atoms. In the fourth O site, O(4) is bonded to one Cr(2), two equivalent Cr(1), and one Zn(1) atom to form OZnCr3 trigonal pyramids that share corners with two equivalent O(4)ZnCr3 trigonal pyramids, edges with two equivalent O(7)Zn2Cr3 square pyramids, and edges with two equivalent O(6)Zn2Cr3 trigonal bipyramids. In the fifth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Cr(4) and two equivalent Cr(1) atoms. In the sixth O site, O(6) is bonded to one Cr(3), two equivalent Cr(2), and two equivalent Zn(1) atoms to form distorted OZn2Cr3 trigonal bipyramids that share corners with two equivalent O(7)Zn2Cr3 square pyramids,  an edgeedge with one O(7)Zn2Cr3 square pyramid, edges with two equivalent O(6)Zn2Cr3 trigonal bipyramids, and edges with two equivalent O(4)ZnCr3 trigonal pyramids. In the seventh O site, O(7) is bonded to one Cr(1), two equivalent Cr(4), and two equivalent Zn(1) atoms to form OZn2Cr3 square pyramids that share corners with two equivalent O(6)Zn2Cr3 trigonal bipyramids, edges with two equivalent O(7)Zn2Cr3 square pyramids,  an edgeedge with one O(6)Zn2Cr3 trigonal bipyramid, and edges with two equivalent O(4)ZnCr3 trigonal pyramids. In the eighth O site, O(8) is bonded in a trigonal non-coplanar geometry to one Cr(2) and two equivalent Cr(3) atoms.