MgZn2(Bi2O5)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted MgO5 trigonal bipyramids that share  a cornercorner with one Zn(1)O6 octahedra, corners with four equivalent Bi(1)O6 octahedra, corners with two equivalent Bi(2)O5 trigonal bipyramids,  an edgeedge with one Zn(1)O6 octahedra, edges with two equivalent Bi(1)O6 octahedra, and  a faceface with one Zn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-78°. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted ZnO6 octahedra that share corners with two equivalent Zn(1)O6 octahedra, corners with two equivalent Bi(1)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, corners with two equivalent Bi(2)O5 trigonal bipyramids, edges with four equivalent Bi(1)O6 octahedra,  an edgeedge with one Mg(1)O5 trigonal bipyramid, and  a faceface with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 1-28°. In the second Zn site, Zn(2) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(3), and two equivalent O(6) atoms. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted BiO6 octahedra that share  a cornercorner with one Zn(1)O6 octahedra, corners with three equivalent Bi(1)O6 octahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids, corners with two equivalent Bi(2)O5 trigonal bipyramids, edges with two equivalent Zn(1)O6 octahedra,  an edgeedge with one Mg(1)O5 trigonal bipyramid, and  an edgeedge with one Bi(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 28-74°. In the second Bi site, Bi(2) is bonded to one O(1), one O(5), one O(6), and two equivalent O(3) atoms to form BiO5 trigonal bipyramids that share  a cornercorner with one Zn(1)O6 octahedra, corners with two equivalent Bi(1)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, corners with three equivalent Bi(2)O5 trigonal bipyramids, and  an edgeedge with one Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 71-84°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Zn(2) and two equivalent Bi(2) atoms. In the second O site, O(2) is bonded to one Mg(1), two equivalent Zn(1), and two equivalent Bi(1) atoms to form OMgZn2Bi2 trigonal bipyramids that share corners with two equivalent O(2)MgZn2Bi2 trigonal bipyramids, corners with two equivalent O(4)MgZnBi2 trigonal pyramids, and edges with four equivalent O(4)MgZnBi2 trigonal pyramids. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Zn(2), one Bi(1), and two equivalent Bi(2) atoms. In the fourth O site, O(4) is bonded to one Mg(1), one Zn(1), and two equivalent Bi(1) atoms to form distorted OMgZnBi2 trigonal pyramids that share  a cornercorner with one O(2)MgZn2Bi2 trigonal bipyramid, corners with two equivalent O(4)MgZnBi2 trigonal pyramids, edges with two equivalent O(2)MgZn2Bi2 trigonal bipyramids, and  an edgeedge with one O(4)MgZnBi2 trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted see-saw-like geometry to one Mg(1), one Zn(1), one Bi(1), and one Bi(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Zn(2), one Bi(1), and one Bi(2) atom.
MgZn2(Bi2O5)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted MgO5 trigonal bipyramids that share  a cornercorner with one Zn(1)O6 octahedra, corners with four equivalent Bi(1)O6 octahedra, corners with two equivalent Bi(2)O5 trigonal bipyramids,  an edgeedge with one Zn(1)O6 octahedra, edges with two equivalent Bi(1)O6 octahedra, and  a faceface with one Zn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-78°. The Mg(1)-O(2) bond length is 2.06 Å. Both Mg(1)-O(4) bond lengths are 2.22 Å. Both Mg(1)-O(5) bond lengths are 2.17 Å. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted ZnO6 octahedra that share corners with two equivalent Zn(1)O6 octahedra, corners with two equivalent Bi(1)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, corners with two equivalent Bi(2)O5 trigonal bipyramids, edges with four equivalent Bi(1)O6 octahedra,  an edgeedge with one Mg(1)O5 trigonal bipyramid, and  a faceface with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 1-28°. There is one shorter (2.08 Å) and one longer (2.40 Å) Zn(1)-O(2) bond length. Both Zn(1)-O(4) bond lengths are 2.14 Å. Both Zn(1)-O(5) bond lengths are 2.11 Å. In the second Zn site, Zn(2) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(3), and two equivalent O(6) atoms. The Zn(2)-O(1) bond length is 2.09 Å. Both Zn(2)-O(3) bond lengths are 2.34 Å. Both Zn(2)-O(6) bond lengths are 2.03 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted BiO6 octahedra that share  a cornercorner with one Zn(1)O6 octahedra, corners with three equivalent Bi(1)O6 octahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids, corners with two equivalent Bi(2)O5 trigonal bipyramids, edges with two equivalent Zn(1)O6 octahedra,  an edgeedge with one Mg(1)O5 trigonal bipyramid, and  an edgeedge with one Bi(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 28-74°. The Bi(1)-O(2) bond length is 2.48 Å. The Bi(1)-O(3) bond length is 2.39 Å. The Bi(1)-O(5) bond length is 2.29 Å. The Bi(1)-O(6) bond length is 2.28 Å. There is one shorter (2.31 Å) and one longer (2.33 Å) Bi(1)-O(4) bond length. In the second Bi site, Bi(2) is bonded to one O(1), one O(5), one O(6), and two equivalent O(3) atoms to form BiO5 trigonal bipyramids that share  a cornercorner with one Zn(1)O6 octahedra, corners with two equivalent Bi(1)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, corners with three equivalent Bi(2)O5 trigonal bipyramids, and  an edgeedge with one Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 71-84°. The Bi(2)-O(1) bond length is 2.22 Å. The Bi(2)-O(5) bond length is 2.38 Å. The Bi(2)-O(6) bond length is 2.12 Å. There is one shorter (2.28 Å) and one longer (2.35 Å) Bi(2)-O(3) bond length. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Zn(2) and two equivalent Bi(2) atoms. In the second O site, O(2) is bonded to one Mg(1), two equivalent Zn(1), and two equivalent Bi(1) atoms to form OMgZn2Bi2 trigonal bipyramids that share corners with two equivalent O(2)MgZn2Bi2 trigonal bipyramids, corners with two equivalent O(4)MgZnBi2 trigonal pyramids, and edges with four equivalent O(4)MgZnBi2 trigonal pyramids. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Zn(2), one Bi(1), and two equivalent Bi(2) atoms. In the fourth O site, O(4) is bonded to one Mg(1), one Zn(1), and two equivalent Bi(1) atoms to form distorted OMgZnBi2 trigonal pyramids that share  a cornercorner with one O(2)MgZn2Bi2 trigonal bipyramid, corners with two equivalent O(4)MgZnBi2 trigonal pyramids, edges with two equivalent O(2)MgZn2Bi2 trigonal bipyramids, and  an edgeedge with one O(4)MgZnBi2 trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted see-saw-like geometry to one Mg(1), one Zn(1), one Bi(1), and one Bi(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Zn(2), one Bi(1), and one Bi(2) atom.