MgY2(CoO3)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to three equivalent O(1) and three equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with three equivalent Co(2)O4 tetrahedra, edges with six equivalent Mg(1)O6 octahedra, and edges with three equivalent Co(2)O4 tetrahedra. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(6), three equivalent O(1), and three equivalent O(3) atoms. In the second Y site, Y(2) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form YO6 octahedra that share corners with three equivalent Co(2)O4 tetrahedra, corners with three equivalent Co(1)O5 trigonal bipyramids, and edges with six equivalent Y(2)O6 octahedra. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one O(3), and three equivalent O(6) atoms to form CoO5 trigonal bipyramids that share corners with three equivalent Y(2)O6 octahedra and corners with six equivalent Co(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 65°. In the second Co site, Co(2) is bonded to one O(4) and three equivalent O(5) atoms to form CoO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Y(2)O6 octahedra, corners with six equivalent Co(2)O4 tetrahedra, and edges with three equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-60°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to three equivalent Mg(1) and three equivalent Y(1) atoms. In the second O site, O(2) is bonded to three equivalent Y(2) and one Co(1) atom to form OY3Co tetrahedra that share  a cornercorner with one O(3)Y3Co tetrahedra, corners with six equivalent O(2)Y3Co tetrahedra, corners with three equivalent O(4)Y3Co trigonal pyramids, corners with three equivalent O(6)YCo3 trigonal pyramids, and edges with three equivalent O(4)Y3Co trigonal pyramids. In the third O site, O(3) is bonded to three equivalent Y(1) and one Co(1) atom to form distorted OY3Co tetrahedra that share  a cornercorner with one O(2)Y3Co tetrahedra, corners with six equivalent O(3)Y3Co tetrahedra, and edges with three equivalent O(6)YCo3 trigonal pyramids. In the fourth O site, O(4) is bonded to three equivalent Y(2) and one Co(2) atom to form distorted OY3Co trigonal pyramids that share corners with three equivalent O(5)Mg3Co3 octahedra, corners with three equivalent O(2)Y3Co tetrahedra, corners with six equivalent O(4)Y3Co trigonal pyramids, and edges with three equivalent O(2)Y3Co tetrahedra. The corner-sharing octahedral tilt angles are 70°. In the fifth O site, O(5) is bonded to three equivalent Mg(1) and three equivalent Co(2) atoms to form distorted OMg3Co3 octahedra that share corners with three equivalent O(4)Y3Co trigonal pyramids and edges with six equivalent O(5)Mg3Co3 octahedra. In the sixth O site, O(6) is bonded to one Y(1) and three equivalent Co(1) atoms to form distorted OYCo3 trigonal pyramids that share corners with three equivalent O(2)Y3Co tetrahedra, corners with six equivalent O(6)YCo3 trigonal pyramids, and edges with three equivalent O(3)Y3Co tetrahedra.
MgY2(CoO3)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to three equivalent O(1) and three equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with three equivalent Co(2)O4 tetrahedra, edges with six equivalent Mg(1)O6 octahedra, and edges with three equivalent Co(2)O4 tetrahedra. There is one shorter (2.19 Å) and two longer (2.20 Å) Mg(1)-O(1) bond lengths. There are two shorter (2.45 Å) and one longer (2.47 Å) Mg(1)-O(5) bond length. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(6), three equivalent O(1), and three equivalent O(3) atoms. The Y(1)-O(6) bond length is 2.33 Å. All Y(1)-O(1) bond lengths are 2.71 Å. All Y(1)-O(3) bond lengths are 2.08 Å. In the second Y site, Y(2) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form YO6 octahedra that share corners with three equivalent Co(2)O4 tetrahedra, corners with three equivalent Co(1)O5 trigonal bipyramids, and edges with six equivalent Y(2)O6 octahedra. All Y(2)-O(2) bond lengths are 2.24 Å. All Y(2)-O(4) bond lengths are 2.36 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one O(3), and three equivalent O(6) atoms to form CoO5 trigonal bipyramids that share corners with three equivalent Y(2)O6 octahedra and corners with six equivalent Co(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 65°. The Co(1)-O(2) bond length is 2.04 Å. The Co(1)-O(3) bond length is 2.27 Å. All Co(1)-O(6) bond lengths are 2.07 Å. In the second Co site, Co(2) is bonded to one O(4) and three equivalent O(5) atoms to form CoO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Y(2)O6 octahedra, corners with six equivalent Co(2)O4 tetrahedra, and edges with three equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-60°. The Co(2)-O(4) bond length is 1.88 Å. All Co(2)-O(5) bond lengths are 2.16 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to three equivalent Mg(1) and three equivalent Y(1) atoms. In the second O site, O(2) is bonded to three equivalent Y(2) and one Co(1) atom to form OY3Co tetrahedra that share  a cornercorner with one O(3)Y3Co tetrahedra, corners with six equivalent O(2)Y3Co tetrahedra, corners with three equivalent O(4)Y3Co trigonal pyramids, corners with three equivalent O(6)YCo3 trigonal pyramids, and edges with three equivalent O(4)Y3Co trigonal pyramids. In the third O site, O(3) is bonded to three equivalent Y(1) and one Co(1) atom to form distorted OY3Co tetrahedra that share  a cornercorner with one O(2)Y3Co tetrahedra, corners with six equivalent O(3)Y3Co tetrahedra, and edges with three equivalent O(6)YCo3 trigonal pyramids. In the fourth O site, O(4) is bonded to three equivalent Y(2) and one Co(2) atom to form distorted OY3Co trigonal pyramids that share corners with three equivalent O(5)Mg3Co3 octahedra, corners with three equivalent O(2)Y3Co tetrahedra, corners with six equivalent O(4)Y3Co trigonal pyramids, and edges with three equivalent O(2)Y3Co tetrahedra. The corner-sharing octahedral tilt angles are 70°. In the fifth O site, O(5) is bonded to three equivalent Mg(1) and three equivalent Co(2) atoms to form distorted OMg3Co3 octahedra that share corners with three equivalent O(4)Y3Co trigonal pyramids and edges with six equivalent O(5)Mg3Co3 octahedra. In the sixth O site, O(6) is bonded to one Y(1) and three equivalent Co(1) atoms to form distorted OYCo3 trigonal pyramids that share corners with three equivalent O(2)Y3Co tetrahedra, corners with six equivalent O(6)YCo3 trigonal pyramids, and edges with three equivalent O(3)Y3Co tetrahedra.