MgTb5(MoO6)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(9) atom. There are five inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 6-coordinate geometry to one O(12), one O(3), one O(4), one O(6), one O(7), and one O(8) atom. In the second Tb site, Tb(2) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(2), one O(5), one O(6), one O(7), and one O(8) atom. In the third Tb site, Tb(3) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. In the fourth Tb site, Tb(4) is bonded in a 6-coordinate geometry to one O(12), one O(2), one O(3), one O(4), one O(7), and one O(8) atom. In the fifth Tb site, Tb(5) is bonded to one O(10), one O(5), one O(6), one O(7), one O(8), and one O(9) atom to form TbO6 octahedra that share corners with two equivalent Mo(1)O6 octahedra and corners with two equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-54°. 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(12), one O(4), and one O(9) atom to form MoO6 octahedra that share corners with two equivalent Tb(5)O6 octahedra and edges with two equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-54°. In the second Mo site, Mo(2) is bonded to one O(10), one O(11), one O(12), one O(2), one O(3), and one O(9) atom to form MoO6 octahedra that share corners with two equivalent Tb(5)O6 octahedra and edges with two equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-46°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Tb(2), one Tb(3), and one Mo(1) atom. In the second O site, O(2) is bonded to one Mg(1), one Tb(2), one Tb(3), one Tb(4), and one Mo(2) atom to form distorted OTb3MgMo trigonal bipyramids that share corners with two equivalent O(7)Tb4 tetrahedra, corners with two equivalent O(8)Tb4 tetrahedra,  a cornercorner with one O(5)Tb3Mg trigonal pyramid,  an edgeedge with one O(12)Tb2Mo2 trigonal pyramid,  an edgeedge with one O(5)Tb3Mg trigonal pyramid, and  a faceface with one O(4)Tb3MgMo square pyramid. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Mg(1), one Tb(1), one Tb(3), one Tb(4), and one Mo(2) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Tb(1), one Tb(3), one Tb(4), and one Mo(1) atom to form distorted OTb3MgMo square pyramids that share corners with two equivalent O(7)Tb4 tetrahedra,  a cornercorner with one O(12)Tb2Mo2 trigonal pyramid, corners with two equivalent O(5)Tb3Mg trigonal pyramids,  an edgeedge with one O(8)Tb4 tetrahedra,  an edgeedge with one O(12)Tb2Mo2 trigonal pyramid, and  a faceface with one O(2)Tb3MgMo trigonal bipyramid. In the fifth O site, O(5) is bonded to one Mg(1), one Tb(2), one Tb(3), and one Tb(5) atom to form distorted OTb3Mg trigonal pyramids that share corners with two equivalent O(4)Tb3MgMo square pyramids, corners with two equivalent O(7)Tb4 tetrahedra, corners with two equivalent O(8)Tb4 tetrahedra,  a cornercorner with one O(2)Tb3MgMo trigonal bipyramid, and  an edgeedge with one O(2)Tb3MgMo trigonal bipyramid. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Tb(1), one Tb(2), one Tb(3), and one Tb(5) atom. In the seventh O site, O(7) is bonded to one Tb(1), one Tb(2), one Tb(4), and one Tb(5) atom to form OTb4 tetrahedra that share corners with two equivalent O(4)Tb3MgMo square pyramids, corners with two equivalent O(2)Tb3MgMo trigonal bipyramids, corners with two equivalent O(12)Tb2Mo2 trigonal pyramids, corners with two equivalent O(5)Tb3Mg trigonal pyramids, and edges with two equivalent O(8)Tb4 tetrahedra. In the eighth O site, O(8) is bonded to one Tb(1), one Tb(2), one Tb(4), and one Tb(5) atom to form OTb4 tetrahedra that share corners with two equivalent O(2)Tb3MgMo trigonal bipyramids, corners with two equivalent O(12)Tb2Mo2 trigonal pyramids, corners with two equivalent O(5)Tb3Mg trigonal pyramids,  an edgeedge with one O(4)Tb3MgMo square pyramid, and edges with two equivalent O(7)Tb4 tetrahedra. In the ninth O site, O(9) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Tb(5), one Mo(1), and one Mo(2) atom. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one Tb(5), one Mo(1), and one Mo(2) atom. In the eleventh O site, O(11) is bonded in a rectangular see-saw-like geometry to one Tb(2), one Tb(3), one Mo(1), and one Mo(2) atom. In the twelfth O site, O(12) is bonded to one Tb(1), one Tb(4), one Mo(1), and one Mo(2) atom to form OTb2Mo2 trigonal pyramids that share  a cornercorner with one O(4)Tb3MgMo square pyramid, corners with two equivalent O(7)Tb4 tetrahedra, corners with two equivalent O(8)Tb4 tetrahedra,  an edgeedge with one O(4)Tb3MgMo square pyramid, and  an edgeedge with one O(2)Tb3MgMo trigonal bipyramid.
MgTb5(MoO6)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(9) atom. The Mg(1)-O(1) bond length is 2.58 Å. The Mg(1)-O(2) bond length is 2.08 Å. The Mg(1)-O(3) bond length is 2.01 Å. The Mg(1)-O(4) bond length is 2.54 Å. The Mg(1)-O(5) bond length is 2.04 Å. The Mg(1)-O(9) bond length is 1.97 Å. There are five inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 6-coordinate geometry to one O(12), one O(3), one O(4), one O(6), one O(7), and one O(8) atom. The Tb(1)-O(12) bond length is 2.38 Å. The Tb(1)-O(3) bond length is 2.50 Å. The Tb(1)-O(4) bond length is 2.32 Å. The Tb(1)-O(6) bond length is 2.28 Å. The Tb(1)-O(7) bond length is 2.31 Å. The Tb(1)-O(8) bond length is 2.33 Å. In the second Tb site, Tb(2) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(2), one O(5), one O(6), one O(7), and one O(8) atom. The Tb(2)-O(1) bond length is 2.39 Å. The Tb(2)-O(11) bond length is 2.33 Å. The Tb(2)-O(2) bond length is 2.37 Å. The Tb(2)-O(5) bond length is 2.31 Å. The Tb(2)-O(6) bond length is 2.70 Å. The Tb(2)-O(7) bond length is 2.34 Å. The Tb(2)-O(8) bond length is 2.31 Å. In the third Tb site, Tb(3) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. The Tb(3)-O(1) bond length is 2.21 Å. The Tb(3)-O(11) bond length is 2.34 Å. The Tb(3)-O(2) bond length is 2.42 Å. The Tb(3)-O(3) bond length is 2.73 Å. The Tb(3)-O(4) bond length is 2.43 Å. The Tb(3)-O(5) bond length is 2.42 Å. The Tb(3)-O(6) bond length is 2.28 Å. In the fourth Tb site, Tb(4) is bonded in a 6-coordinate geometry to one O(12), one O(2), one O(3), one O(4), one O(7), and one O(8) atom. The Tb(4)-O(12) bond length is 2.26 Å. The Tb(4)-O(2) bond length is 2.44 Å. The Tb(4)-O(3) bond length is 2.35 Å. The Tb(4)-O(4) bond length is 2.48 Å. The Tb(4)-O(7) bond length is 2.28 Å. The Tb(4)-O(8) bond length is 2.22 Å. In the fifth Tb site, Tb(5) is bonded to one O(10), one O(5), one O(6), one O(7), one O(8), and one O(9) atom to form TbO6 octahedra that share corners with two equivalent Mo(1)O6 octahedra and corners with two equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-54°. The Tb(5)-O(10) bond length is 2.29 Å. The Tb(5)-O(5) bond length is 2.32 Å. The Tb(5)-O(6) bond length is 2.36 Å. The Tb(5)-O(7) bond length is 2.39 Å. The Tb(5)-O(8) bond length is 2.37 Å. The Tb(5)-O(9) bond length is 2.39 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(12), one O(4), and one O(9) atom to form MoO6 octahedra that share corners with two equivalent Tb(5)O6 octahedra and edges with two equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-54°. The Mo(1)-O(1) bond length is 1.97 Å. The Mo(1)-O(10) bond length is 2.01 Å. The Mo(1)-O(11) bond length is 2.11 Å. The Mo(1)-O(12) bond length is 2.15 Å. The Mo(1)-O(4) bond length is 2.09 Å. The Mo(1)-O(9) bond length is 2.14 Å. In the second Mo site, Mo(2) is bonded to one O(10), one O(11), one O(12), one O(2), one O(3), and one O(9) atom to form MoO6 octahedra that share corners with two equivalent Tb(5)O6 octahedra and edges with two equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-46°. The Mo(2)-O(10) bond length is 2.16 Å. The Mo(2)-O(11) bond length is 2.15 Å. The Mo(2)-O(12) bond length is 2.16 Å. The Mo(2)-O(2) bond length is 2.22 Å. The Mo(2)-O(3) bond length is 2.16 Å. The Mo(2)-O(9) bond length is 2.18 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Tb(2), one Tb(3), and one Mo(1) atom. In the second O site, O(2) is bonded to one Mg(1), one Tb(2), one Tb(3), one Tb(4), and one Mo(2) atom to form distorted OTb3MgMo trigonal bipyramids that share corners with two equivalent O(7)Tb4 tetrahedra, corners with two equivalent O(8)Tb4 tetrahedra,  a cornercorner with one O(5)Tb3Mg trigonal pyramid,  an edgeedge with one O(12)Tb2Mo2 trigonal pyramid,  an edgeedge with one O(5)Tb3Mg trigonal pyramid, and  a faceface with one O(4)Tb3MgMo square pyramid. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Mg(1), one Tb(1), one Tb(3), one Tb(4), and one Mo(2) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Tb(1), one Tb(3), one Tb(4), and one Mo(1) atom to form distorted OTb3MgMo square pyramids that share corners with two equivalent O(7)Tb4 tetrahedra,  a cornercorner with one O(12)Tb2Mo2 trigonal pyramid, corners with two equivalent O(5)Tb3Mg trigonal pyramids,  an edgeedge with one O(8)Tb4 tetrahedra,  an edgeedge with one O(12)Tb2Mo2 trigonal pyramid, and  a faceface with one O(2)Tb3MgMo trigonal bipyramid. In the fifth O site, O(5) is bonded to one Mg(1), one Tb(2), one Tb(3), and one Tb(5) atom to form distorted OTb3Mg trigonal pyramids that share corners with two equivalent O(4)Tb3MgMo square pyramids, corners with two equivalent O(7)Tb4 tetrahedra, corners with two equivalent O(8)Tb4 tetrahedra,  a cornercorner with one O(2)Tb3MgMo trigonal bipyramid, and  an edgeedge with one O(2)Tb3MgMo trigonal bipyramid. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Tb(1), one Tb(2), one Tb(3), and one Tb(5) atom. In the seventh O site, O(7) is bonded to one Tb(1), one Tb(2), one Tb(4), and one Tb(5) atom to form OTb4 tetrahedra that share corners with two equivalent O(4)Tb3MgMo square pyramids, corners with two equivalent O(2)Tb3MgMo trigonal bipyramids, corners with two equivalent O(12)Tb2Mo2 trigonal pyramids, corners with two equivalent O(5)Tb3Mg trigonal pyramids, and edges with two equivalent O(8)Tb4 tetrahedra. In the eighth O site, O(8) is bonded to one Tb(1), one Tb(2), one Tb(4), and one Tb(5) atom to form OTb4 tetrahedra that share corners with two equivalent O(2)Tb3MgMo trigonal bipyramids, corners with two equivalent O(12)Tb2Mo2 trigonal pyramids, corners with two equivalent O(5)Tb3Mg trigonal pyramids,  an edgeedge with one O(4)Tb3MgMo square pyramid, and edges with two equivalent O(7)Tb4 tetrahedra. In the ninth O site, O(9) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Tb(5), one Mo(1), and one Mo(2) atom. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one Tb(5), one Mo(1), and one Mo(2) atom. In the eleventh O site, O(11) is bonded in a rectangular see-saw-like geometry to one Tb(2), one Tb(3), one Mo(1), and one Mo(2) atom. In the twelfth O site, O(12) is bonded to one Tb(1), one Tb(4), one Mo(1), and one Mo(2) atom to form OTb2Mo2 trigonal pyramids that share  a cornercorner with one O(4)Tb3MgMo square pyramid, corners with two equivalent O(7)Tb4 tetrahedra, corners with two equivalent O(8)Tb4 tetrahedra,  an edgeedge with one O(4)Tb3MgMo square pyramid, and  an edgeedge with one O(2)Tb3MgMo trigonal bipyramid.