MgYMo3O8 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share edges with two equivalent Mo(1)O6 octahedra, edges with two equivalent Mo(2)O6 octahedra, edges with two equivalent Mo(3)O6 octahedra, and faces with two equivalent Y(1)O6 octahedra. Y(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted YO6 octahedra that share corners with four equivalent Mo(1)O6 octahedra, corners with four equivalent Mo(2)O6 octahedra, corners with four equivalent Mo(3)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-48°. There are three inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MoO6 octahedra that share corners with four equivalent Y(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mo(2)O6 octahedra, and edges with two equivalent Mo(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-48°. In the second Mo site, Mo(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MoO6 octahedra that share corners with four equivalent Y(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mo(1)O6 octahedra, and edges with two equivalent Mo(3)O6 octahedra. The corner-sharing octahedral tilt angles are 46°. In the third Mo site, Mo(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form MoO6 octahedra that share corners with four equivalent Y(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mo(1)O6 octahedra, and edges with two equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-47°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Y(1), one Mo(2), and one Mo(3) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Mo(1), one Mo(2), and one Mo(3) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Y(1), one Mo(1), and one Mo(2) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Y(1), one Mo(1), and one Mo(3) atom.
MgYMo3O8 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share edges with two equivalent Mo(1)O6 octahedra, edges with two equivalent Mo(2)O6 octahedra, edges with two equivalent Mo(3)O6 octahedra, and faces with two equivalent Y(1)O6 octahedra. Both Mg(1)-O(1) bond lengths are 2.06 Å. Both Mg(1)-O(3) bond lengths are 2.06 Å. Both Mg(1)-O(4) bond lengths are 2.07 Å. Y(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted YO6 octahedra that share corners with four equivalent Mo(1)O6 octahedra, corners with four equivalent Mo(2)O6 octahedra, corners with four equivalent Mo(3)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-48°. Both Y(1)-O(1) bond lengths are 2.36 Å. Both Y(1)-O(3) bond lengths are 2.36 Å. Both Y(1)-O(4) bond lengths are 2.37 Å. There are three inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MoO6 octahedra that share corners with four equivalent Y(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mo(2)O6 octahedra, and edges with two equivalent Mo(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-48°. Both Mo(1)-O(2) bond lengths are 2.13 Å. Both Mo(1)-O(3) bond lengths are 2.20 Å. Both Mo(1)-O(4) bond lengths are 2.20 Å. In the second Mo site, Mo(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MoO6 octahedra that share corners with four equivalent Y(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mo(1)O6 octahedra, and edges with two equivalent Mo(3)O6 octahedra. The corner-sharing octahedral tilt angles are 46°. Both Mo(2)-O(1) bond lengths are 2.15 Å. Both Mo(2)-O(2) bond lengths are 2.04 Å. Both Mo(2)-O(3) bond lengths are 2.11 Å. In the third Mo site, Mo(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form MoO6 octahedra that share corners with four equivalent Y(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mo(1)O6 octahedra, and edges with two equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-47°. Both Mo(3)-O(1) bond lengths are 2.20 Å. Both Mo(3)-O(2) bond lengths are 2.04 Å. Both Mo(3)-O(4) bond lengths are 2.10 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Y(1), one Mo(2), and one Mo(3) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Mo(1), one Mo(2), and one Mo(3) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Y(1), one Mo(1), and one Mo(2) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Y(1), one Mo(1), and one Mo(3) atom.