MgY5(MoO6)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(11), one O(3), one O(6), one O(7), and one O(8) atom to form MgO5 square pyramids that share  an edgeedge with one Mo(1)O6 octahedra,  an edgeedge with one Mo(2)O6 octahedra, edges with two equivalent Y(5)O7 pentagonal bipyramids, and  a faceface with one Y(1)O6 octahedra. There are five inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(12), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form distorted YO6 octahedra that share corners with two equivalent Mo(1)O6 octahedra, corners with two equivalent Mo(2)O6 octahedra, corners with two equivalent Y(5)O7 pentagonal bipyramids,  an edgeedge with one Y(5)O7 pentagonal bipyramid, and  a faceface with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 41-45°. In the second Y site, Y(2) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(11), one O(6), one O(7), one O(8), and one O(9) atom. In the third Y site, Y(3) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(12), one O(2), one O(5), one O(8), and one O(9) atom. In the fourth Y site, Y(4) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(12), one O(5), one O(6), one O(7), and one O(9) atom. In the fifth Y site, Y(5) is bonded to one O(11), one O(12), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Y(1)O6 octahedra,  an edgeedge with one Y(1)O6 octahedra,  an edgeedge with one Mo(1)O6 octahedra,  an edgeedge with one Mo(2)O6 octahedra, and edges with two equivalent Mg(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 48°. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(1), one O(10), one O(11), one O(2), one O(3), and one O(4) atom to form MoO6 octahedra that share corners with two equivalent Y(1)O6 octahedra, edges with two equivalent Mo(2)O6 octahedra,  an edgeedge with one Y(5)O7 pentagonal bipyramid, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 42-45°. In the second Mo site, Mo(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(8), and one O(9) atom to form MoO6 octahedra that share corners with two equivalent Y(1)O6 octahedra, edges with two equivalent Mo(1)O6 octahedra,  an edgeedge with one Y(5)O7 pentagonal bipyramid, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 41-44°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Y(2), one Y(4), one Mo(1), and one Mo(2) atom. In the second O site, O(2) is bonded to one Y(3), one Y(5), one Mo(1), and one Mo(2) atom to form distorted OY2Mo2 trigonal pyramids that share corners with two equivalent O(12)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra,  a cornercorner with one O(6)Y4Mg trigonal bipyramid,  a cornercorner with one O(7)Y4Mg trigonal bipyramid,  a cornercorner with one O(8)Y3MgMo trigonal pyramid,  an edgeedge with one O(10)Y3Mo tetrahedra,  an edgeedge with one O(9)Y3Mo tetrahedra, and  an edgeedge with one O(8)Y3MgMo trigonal pyramid. 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 distorted T-shaped geometry to one Y(1), one Mo(1), and one Mo(2) atom. In the fifth O site, O(5) is bonded to one Y(1), one Y(3), one Y(4), and one Y(5) atom to form distorted OY4 tetrahedra that share corners with two equivalent O(10)Y3Mo tetrahedra, corners with two equivalent O(9)Y3Mo tetrahedra,  a cornercorner with one O(7)Y4Mg trigonal bipyramid, corners with three equivalent O(6)Y4Mg trigonal bipyramids, corners with two equivalent O(2)Y2Mo2 trigonal pyramids, edges with two equivalent O(12)Y4 tetrahedra,  an edgeedge with one O(7)Y4Mg trigonal bipyramid, and  an edgeedge with one O(8)Y3MgMo trigonal pyramid. In the sixth O site, O(6) is bonded to one Mg(1), one Y(1), one Y(2), one Y(4), and one Y(5) atom to form distorted OY4Mg trigonal bipyramids that share  a cornercorner with one O(12)Y4 tetrahedra, corners with two equivalent O(10)Y3Mo tetrahedra, corners with three equivalent O(5)Y4 tetrahedra,  a cornercorner with one O(2)Y2Mo2 trigonal pyramid, corners with three equivalent O(8)Y3MgMo trigonal pyramids,  an edgeedge with one O(9)Y3Mo tetrahedra,  an edgeedge with one O(12)Y4 tetrahedra,  an edgeedge with one O(7)Y4Mg trigonal bipyramid, and  a faceface with one O(7)Y4Mg trigonal bipyramid. In the seventh O site, O(7) is bonded to one Mg(1), one Y(1), one Y(2), one Y(4), and one Y(5) atom to form distorted OY4Mg trigonal bipyramids that share  a cornercorner with one O(5)Y4 tetrahedra, corners with two equivalent O(9)Y3Mo tetrahedra, corners with three equivalent O(12)Y4 tetrahedra,  a cornercorner with one O(2)Y2Mo2 trigonal pyramid,  a cornercorner with one O(8)Y3MgMo trigonal pyramid,  an edgeedge with one O(10)Y3Mo tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra,  an edgeedge with one O(6)Y4Mg trigonal bipyramid,  an edgeedge with one O(8)Y3MgMo trigonal pyramid, and  a faceface with one O(6)Y4Mg trigonal bipyramid. In the eighth O site, O(8) is bonded to one Mg(1), one Y(2), one Y(3), one Y(5), and one Mo(2) atom to form distorted OY3MgMo trigonal pyramids that share corners with two equivalent O(12)Y4 tetrahedra, corners with three equivalent O(9)Y3Mo tetrahedra,  a cornercorner with one O(7)Y4Mg trigonal bipyramid, corners with three equivalent O(6)Y4Mg trigonal bipyramids,  a cornercorner with one O(2)Y2Mo2 trigonal pyramid,  an edgeedge with one O(10)Y3Mo tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra,  an edgeedge with one O(7)Y4Mg trigonal bipyramid, and  an edgeedge with one O(2)Y2Mo2 trigonal pyramid. In the ninth O site, O(9) is bonded to one Y(2), one Y(3), one Y(4), and one Mo(2) atom to form OY3Mo tetrahedra that share  a cornercorner with one O(10)Y3Mo tetrahedra, corners with two equivalent O(12)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with two equivalent O(7)Y4Mg trigonal bipyramids, corners with three equivalent O(8)Y3MgMo trigonal pyramids,  an edgeedge with one O(10)Y3Mo tetrahedra,  an edgeedge with one O(6)Y4Mg trigonal bipyramid, and  an edgeedge with one O(2)Y2Mo2 trigonal pyramid. In the tenth O site, O(10) is bonded to one Y(2), one Y(3), one Y(4), and one Mo(1) atom to form OY3Mo tetrahedra that share  a cornercorner with one O(9)Y3Mo tetrahedra, corners with two equivalent O(12)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with two equivalent O(6)Y4Mg trigonal bipyramids,  an edgeedge with one O(9)Y3Mo tetrahedra,  an edgeedge with one O(7)Y4Mg trigonal bipyramid,  an edgeedge with one O(2)Y2Mo2 trigonal pyramid, and  an edgeedge with one O(8)Y3MgMo trigonal pyramid. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one Mg(1), one Y(2), one Y(3), one Y(5), and one Mo(1) atom. In the twelfth O site, O(12) is bonded to one Y(1), one Y(3), one Y(4), and one Y(5) atom to form distorted OY4 tetrahedra that share corners with two equivalent O(10)Y3Mo tetrahedra, corners with two equivalent O(9)Y3Mo tetrahedra,  a cornercorner with one O(6)Y4Mg trigonal bipyramid, corners with three equivalent O(7)Y4Mg trigonal bipyramids, corners with two equivalent O(2)Y2Mo2 trigonal pyramids, corners with two equivalent O(8)Y3MgMo trigonal pyramids, edges with two equivalent O(5)Y4 tetrahedra, and  an edgeedge with one O(6)Y4Mg trigonal bipyramid.
MgY5(MoO6)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(11), one O(3), one O(6), one O(7), and one O(8) atom to form MgO5 square pyramids that share  an edgeedge with one Mo(1)O6 octahedra,  an edgeedge with one Mo(2)O6 octahedra, edges with two equivalent Y(5)O7 pentagonal bipyramids, and  a faceface with one Y(1)O6 octahedra. The Mg(1)-O(11) bond length is 2.12 Å. The Mg(1)-O(3) bond length is 1.96 Å. The Mg(1)-O(6) bond length is 2.13 Å. The Mg(1)-O(7) bond length is 2.15 Å. The Mg(1)-O(8) bond length is 2.10 Å. There are five inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(12), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form distorted YO6 octahedra that share corners with two equivalent Mo(1)O6 octahedra, corners with two equivalent Mo(2)O6 octahedra, corners with two equivalent Y(5)O7 pentagonal bipyramids,  an edgeedge with one Y(5)O7 pentagonal bipyramid, and  a faceface with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 41-45°. The Y(1)-O(12) bond length is 2.21 Å. The Y(1)-O(3) bond length is 2.32 Å. The Y(1)-O(4) bond length is 2.15 Å. The Y(1)-O(5) bond length is 2.20 Å. The Y(1)-O(6) bond length is 2.64 Å. The Y(1)-O(7) bond length is 2.64 Å. In the second Y site, Y(2) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(11), one O(6), one O(7), one O(8), and one O(9) atom. The Y(2)-O(1) bond length is 2.36 Å. The Y(2)-O(10) bond length is 2.27 Å. The Y(2)-O(11) bond length is 2.96 Å. The Y(2)-O(6) bond length is 2.41 Å. The Y(2)-O(7) bond length is 2.44 Å. The Y(2)-O(8) bond length is 3.03 Å. The Y(2)-O(9) bond length is 2.27 Å. In the third Y site, Y(3) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(12), one O(2), one O(5), one O(8), and one O(9) atom. The Y(3)-O(10) bond length is 2.38 Å. The Y(3)-O(11) bond length is 2.33 Å. The Y(3)-O(12) bond length is 2.48 Å. The Y(3)-O(2) bond length is 2.30 Å. The Y(3)-O(5) bond length is 2.51 Å. The Y(3)-O(8) bond length is 2.31 Å. The Y(3)-O(9) bond length is 2.37 Å. In the fourth Y site, Y(4) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(12), one O(5), one O(6), one O(7), and one O(9) atom. The Y(4)-O(1) bond length is 2.46 Å. The Y(4)-O(10) bond length is 2.30 Å. The Y(4)-O(12) bond length is 2.37 Å. The Y(4)-O(5) bond length is 2.38 Å. The Y(4)-O(6) bond length is 2.44 Å. The Y(4)-O(7) bond length is 2.42 Å. The Y(4)-O(9) bond length is 2.30 Å. In the fifth Y site, Y(5) is bonded to one O(11), one O(12), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Y(1)O6 octahedra,  an edgeedge with one Y(1)O6 octahedra,  an edgeedge with one Mo(1)O6 octahedra,  an edgeedge with one Mo(2)O6 octahedra, and edges with two equivalent Mg(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 48°. The Y(5)-O(11) bond length is 2.27 Å. The Y(5)-O(12) bond length is 2.36 Å. The Y(5)-O(2) bond length is 2.58 Å. The Y(5)-O(5) bond length is 2.34 Å. The Y(5)-O(6) bond length is 2.34 Å. The Y(5)-O(7) bond length is 2.34 Å. The Y(5)-O(8) bond length is 2.27 Å. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(1), one O(10), one O(11), one O(2), one O(3), and one O(4) atom to form MoO6 octahedra that share corners with two equivalent Y(1)O6 octahedra, edges with two equivalent Mo(2)O6 octahedra,  an edgeedge with one Y(5)O7 pentagonal bipyramid, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 42-45°. The Mo(1)-O(1) bond length is 2.13 Å. The Mo(1)-O(10) bond length is 2.16 Å. The Mo(1)-O(11) bond length is 2.14 Å. The Mo(1)-O(2) bond length is 2.10 Å. The Mo(1)-O(3) bond length is 2.12 Å. The Mo(1)-O(4) bond length is 2.07 Å. In the second Mo site, Mo(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(8), and one O(9) atom to form MoO6 octahedra that share corners with two equivalent Y(1)O6 octahedra, edges with two equivalent Mo(1)O6 octahedra,  an edgeedge with one Y(5)O7 pentagonal bipyramid, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 41-44°. The Mo(2)-O(1) bond length is 2.12 Å. The Mo(2)-O(2) bond length is 2.08 Å. The Mo(2)-O(3) bond length is 2.10 Å. The Mo(2)-O(4) bond length is 2.05 Å. The Mo(2)-O(8) bond length is 2.13 Å. The Mo(2)-O(9) bond length is 2.16 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Y(2), one Y(4), one Mo(1), and one Mo(2) atom. In the second O site, O(2) is bonded to one Y(3), one Y(5), one Mo(1), and one Mo(2) atom to form distorted OY2Mo2 trigonal pyramids that share corners with two equivalent O(12)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra,  a cornercorner with one O(6)Y4Mg trigonal bipyramid,  a cornercorner with one O(7)Y4Mg trigonal bipyramid,  a cornercorner with one O(8)Y3MgMo trigonal pyramid,  an edgeedge with one O(10)Y3Mo tetrahedra,  an edgeedge with one O(9)Y3Mo tetrahedra, and  an edgeedge with one O(8)Y3MgMo trigonal pyramid. 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 distorted T-shaped geometry to one Y(1), one Mo(1), and one Mo(2) atom. In the fifth O site, O(5) is bonded to one Y(1), one Y(3), one Y(4), and one Y(5) atom to form distorted OY4 tetrahedra that share corners with two equivalent O(10)Y3Mo tetrahedra, corners with two equivalent O(9)Y3Mo tetrahedra,  a cornercorner with one O(7)Y4Mg trigonal bipyramid, corners with three equivalent O(6)Y4Mg trigonal bipyramids, corners with two equivalent O(2)Y2Mo2 trigonal pyramids, edges with two equivalent O(12)Y4 tetrahedra,  an edgeedge with one O(7)Y4Mg trigonal bipyramid, and  an edgeedge with one O(8)Y3MgMo trigonal pyramid. In the sixth O site, O(6) is bonded to one Mg(1), one Y(1), one Y(2), one Y(4), and one Y(5) atom to form distorted OY4Mg trigonal bipyramids that share  a cornercorner with one O(12)Y4 tetrahedra, corners with two equivalent O(10)Y3Mo tetrahedra, corners with three equivalent O(5)Y4 tetrahedra,  a cornercorner with one O(2)Y2Mo2 trigonal pyramid, corners with three equivalent O(8)Y3MgMo trigonal pyramids,  an edgeedge with one O(9)Y3Mo tetrahedra,  an edgeedge with one O(12)Y4 tetrahedra,  an edgeedge with one O(7)Y4Mg trigonal bipyramid, and  a faceface with one O(7)Y4Mg trigonal bipyramid. In the seventh O site, O(7) is bonded to one Mg(1), one Y(1), one Y(2), one Y(4), and one Y(5) atom to form distorted OY4Mg trigonal bipyramids that share  a cornercorner with one O(5)Y4 tetrahedra, corners with two equivalent O(9)Y3Mo tetrahedra, corners with three equivalent O(12)Y4 tetrahedra,  a cornercorner with one O(2)Y2Mo2 trigonal pyramid,  a cornercorner with one O(8)Y3MgMo trigonal pyramid,  an edgeedge with one O(10)Y3Mo tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra,  an edgeedge with one O(6)Y4Mg trigonal bipyramid,  an edgeedge with one O(8)Y3MgMo trigonal pyramid, and  a faceface with one O(6)Y4Mg trigonal bipyramid. In the eighth O site, O(8) is bonded to one Mg(1), one Y(2), one Y(3), one Y(5), and one Mo(2) atom to form distorted OY3MgMo trigonal pyramids that share corners with two equivalent O(12)Y4 tetrahedra, corners with three equivalent O(9)Y3Mo tetrahedra,  a cornercorner with one O(7)Y4Mg trigonal bipyramid, corners with three equivalent O(6)Y4Mg trigonal bipyramids,  a cornercorner with one O(2)Y2Mo2 trigonal pyramid,  an edgeedge with one O(10)Y3Mo tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra,  an edgeedge with one O(7)Y4Mg trigonal bipyramid, and  an edgeedge with one O(2)Y2Mo2 trigonal pyramid. In the ninth O site, O(9) is bonded to one Y(2), one Y(3), one Y(4), and one Mo(2) atom to form OY3Mo tetrahedra that share  a cornercorner with one O(10)Y3Mo tetrahedra, corners with two equivalent O(12)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with two equivalent O(7)Y4Mg trigonal bipyramids, corners with three equivalent O(8)Y3MgMo trigonal pyramids,  an edgeedge with one O(10)Y3Mo tetrahedra,  an edgeedge with one O(6)Y4Mg trigonal bipyramid, and  an edgeedge with one O(2)Y2Mo2 trigonal pyramid. In the tenth O site, O(10) is bonded to one Y(2), one Y(3), one Y(4), and one Mo(1) atom to form OY3Mo tetrahedra that share  a cornercorner with one O(9)Y3Mo tetrahedra, corners with two equivalent O(12)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with two equivalent O(6)Y4Mg trigonal bipyramids,  an edgeedge with one O(9)Y3Mo tetrahedra,  an edgeedge with one O(7)Y4Mg trigonal bipyramid,  an edgeedge with one O(2)Y2Mo2 trigonal pyramid, and  an edgeedge with one O(8)Y3MgMo trigonal pyramid. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one Mg(1), one Y(2), one Y(3), one Y(5), and one Mo(1) atom. In the twelfth O site, O(12) is bonded to one Y(1), one Y(3), one Y(4), and one Y(5) atom to form distorted OY4 tetrahedra that share corners with two equivalent O(10)Y3Mo tetrahedra, corners with two equivalent O(9)Y3Mo tetrahedra,  a cornercorner with one O(6)Y4Mg trigonal bipyramid, corners with three equivalent O(7)Y4Mg trigonal bipyramids, corners with two equivalent O(2)Y2Mo2 trigonal pyramids, corners with two equivalent O(8)Y3MgMo trigonal pyramids, edges with two equivalent O(5)Y4 tetrahedra, and  an edgeedge with one O(6)Y4Mg trigonal bipyramid.