MgCo2(BiO3)4 crystallizes in the monoclinic P2 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Bi(3)O6 octahedra, corners with two equivalent Bi(4)O6 octahedra, edges with two equivalent Bi(1)O6 octahedra, edges with two equivalent Bi(2)O6 octahedra, and faces with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 43°. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form CoO6 octahedra that share corners with four equivalent Bi(3)O6 octahedra, corners with four equivalent Bi(4)O6 octahedra,  an edgeedge with one Bi(1)O6 octahedra, and  an edgeedge with one Bi(2)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. In the second Co site, Co(2) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms to form CoO6 octahedra that share corners with four equivalent Bi(1)O6 octahedra, corners with four equivalent Bi(2)O6 octahedra,  an edgeedge with one Bi(3)O6 octahedra,  an edgeedge with one Bi(4)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-51°. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form BiO6 octahedra that share corners with four equivalent Co(2)O6 octahedra, corners with four equivalent Bi(3)O6 octahedra,  an edgeedge with one Co(1)O6 octahedra,  an edgeedge with one Bi(2)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-62°. In the second Bi site, Bi(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form BiO6 octahedra that share corners with four equivalent Co(2)O6 octahedra, corners with four equivalent Bi(4)O6 octahedra,  an edgeedge with one Co(1)O6 octahedra,  an edgeedge with one Bi(1)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-62°. In the third Bi site, Bi(3) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form BiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Co(1)O6 octahedra, corners with four equivalent Bi(1)O6 octahedra,  an edgeedge with one Co(2)O6 octahedra, and  an edgeedge with one Bi(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-62°. In the fourth Bi site, Bi(4) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form BiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Co(1)O6 octahedra, corners with four equivalent Bi(2)O6 octahedra,  an edgeedge with one Co(2)O6 octahedra, and  an edgeedge with one Bi(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-62°. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Co(2), one Bi(1), and one Bi(2) atom to form a mixture of distorted corner and edge-sharing OMgCoBi2 trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Co(1), one Bi(1), and one Bi(3) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Co(1), one Bi(2), and one Bi(4) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Co(2), one Bi(1), and one Bi(3) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Co(2), one Bi(2), and one Bi(4) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Co(1), one Bi(3), and one Bi(4) atom.
MgCo2(BiO3)4 crystallizes in the monoclinic P2 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Bi(3)O6 octahedra, corners with two equivalent Bi(4)O6 octahedra, edges with two equivalent Bi(1)O6 octahedra, edges with two equivalent Bi(2)O6 octahedra, and faces with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 43°. Both Mg(1)-O(1) bond lengths are 1.96 Å. Both Mg(1)-O(4) bond lengths are 2.14 Å. Both Mg(1)-O(5) bond lengths are 2.14 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form CoO6 octahedra that share corners with four equivalent Bi(3)O6 octahedra, corners with four equivalent Bi(4)O6 octahedra,  an edgeedge with one Bi(1)O6 octahedra, and  an edgeedge with one Bi(2)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. Both Co(1)-O(2) bond lengths are 2.10 Å. Both Co(1)-O(3) bond lengths are 2.09 Å. Both Co(1)-O(6) bond lengths are 2.11 Å. In the second Co site, Co(2) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms to form CoO6 octahedra that share corners with four equivalent Bi(1)O6 octahedra, corners with four equivalent Bi(2)O6 octahedra,  an edgeedge with one Bi(3)O6 octahedra,  an edgeedge with one Bi(4)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-51°. Both Co(2)-O(1) bond lengths are 2.20 Å. Both Co(2)-O(4) bond lengths are 2.05 Å. Both Co(2)-O(5) bond lengths are 2.05 Å. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form BiO6 octahedra that share corners with four equivalent Co(2)O6 octahedra, corners with four equivalent Bi(3)O6 octahedra,  an edgeedge with one Co(1)O6 octahedra,  an edgeedge with one Bi(2)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-62°. Both Bi(1)-O(1) bond lengths are 2.27 Å. Both Bi(1)-O(2) bond lengths are 2.13 Å. Both Bi(1)-O(4) bond lengths are 2.24 Å. In the second Bi site, Bi(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form BiO6 octahedra that share corners with four equivalent Co(2)O6 octahedra, corners with four equivalent Bi(4)O6 octahedra,  an edgeedge with one Co(1)O6 octahedra,  an edgeedge with one Bi(1)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-62°. Both Bi(2)-O(1) bond lengths are 2.27 Å. Both Bi(2)-O(3) bond lengths are 2.13 Å. Both Bi(2)-O(5) bond lengths are 2.23 Å. In the third Bi site, Bi(3) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form BiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Co(1)O6 octahedra, corners with four equivalent Bi(1)O6 octahedra,  an edgeedge with one Co(2)O6 octahedra, and  an edgeedge with one Bi(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-62°. Both Bi(3)-O(2) bond lengths are 2.25 Å. Both Bi(3)-O(4) bond lengths are 2.31 Å. Both Bi(3)-O(6) bond lengths are 2.21 Å. In the fourth Bi site, Bi(4) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form BiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Co(1)O6 octahedra, corners with four equivalent Bi(2)O6 octahedra,  an edgeedge with one Co(2)O6 octahedra, and  an edgeedge with one Bi(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-62°. Both Bi(4)-O(3) bond lengths are 2.26 Å. Both Bi(4)-O(5) bond lengths are 2.33 Å. Both Bi(4)-O(6) bond lengths are 2.22 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Co(2), one Bi(1), and one Bi(2) atom to form a mixture of distorted corner and edge-sharing OMgCoBi2 trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Co(1), one Bi(1), and one Bi(3) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Co(1), one Bi(2), and one Bi(4) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Co(2), one Bi(1), and one Bi(3) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Co(2), one Bi(2), and one Bi(4) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Co(1), one Bi(3), and one Bi(4) atom.