MgTb5(MoO6)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(10), one O(3), one O(4), one O(5), and one O(6) atom to form distorted MgO5 square pyramids that share  an edgeedge with one Mo(1)O6 octahedra,  an edgeedge with one Mo(2)O6 octahedra, and edges with two equivalent Tb(1)O7 pentagonal bipyramids. There are five inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to one O(12), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted TbO7 pentagonal bipyramids that share  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. 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 7-coordinate geometry to one O(1), 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 in a 6-coordinate geometry to one O(10), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. 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 edges with two equivalent Mo(2)O6 octahedra,  an edgeedge with one Tb(1)O7 pentagonal bipyramid, and  an edgeedge with one Mg(1)O5 square pyramid. 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 edges with two equivalent Mo(1)O6 octahedra,  an edgeedge with one Tb(1)O7 pentagonal bipyramid, and  an edgeedge with one Mg(1)O5 square pyramid. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Tb(2), one Tb(3), one Tb(4), and one Mo(1) atom to form OTb3Mo tetrahedra that share  a cornercorner with one O(2)Tb3Mo tetrahedra, corners with two equivalent O(7)Tb4 tetrahedra, corners with two equivalent O(8)Tb4 tetrahedra, corners with two equivalent O(6)Tb4Mg trigonal bipyramids, and  an edgeedge with one O(2)Tb3Mo tetrahedra. In the second O site, O(2) is bonded to one Tb(2), one Tb(3), one Tb(4), and one Mo(2) atom to form OTb3Mo tetrahedra that share  a cornercorner with one O(1)Tb3Mo tetrahedra, corners with two equivalent O(7)Tb4 tetrahedra, corners with two equivalent O(8)Tb4 tetrahedra,  an edgeedge with one O(1)Tb3Mo tetrahedra, and  an edgeedge with one O(6)Tb4Mg trigonal bipyramid. 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 in a 5-coordinate geometry to one Mg(1), one Tb(1), one Tb(3), one Tb(4), and one Mo(1) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(1), one Tb(1), one Tb(2), one Tb(3), and one Tb(5) atom. In the sixth O site, O(6) is bonded to one Mg(1), one Tb(1), one Tb(2), one Tb(3), and one Tb(5) atom to form distorted OTb4Mg trigonal bipyramids that share  a cornercorner with one O(8)Tb4 tetrahedra, corners with two equivalent O(1)Tb3Mo tetrahedra, corners with three equivalent O(7)Tb4 tetrahedra,  an edgeedge with one O(2)Tb3Mo tetrahedra, and  an edgeedge with one O(8)Tb4 tetrahedra. 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 distorted OTb4 tetrahedra that share corners with two equivalent O(1)Tb3Mo tetrahedra, corners with two equivalent O(2)Tb3Mo tetrahedra, corners with three equivalent O(6)Tb4Mg trigonal bipyramids, 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(1)Tb3Mo tetrahedra, corners with two equivalent O(2)Tb3Mo tetrahedra,  a cornercorner with one O(6)Tb4Mg trigonal bipyramid, edges with two equivalent O(7)Tb4 tetrahedra, and  an edgeedge with one O(6)Tb4Mg trigonal bipyramid. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Tb(5), one Mo(1), and one Mo(2) atom. In the tenth O site, O(10) 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 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 in a rectangular see-saw-like geometry to one Tb(1), one Tb(4), one Mo(1), and one Mo(2) atom.
MgTb5(MoO6)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(10), one O(3), one O(4), one O(5), and one O(6) atom to form distorted MgO5 square pyramids that share  an edgeedge with one Mo(1)O6 octahedra,  an edgeedge with one Mo(2)O6 octahedra, and edges with two equivalent Tb(1)O7 pentagonal bipyramids. The Mg(1)-O(10) bond length is 1.93 Å. The Mg(1)-O(3) bond length is 2.11 Å. The Mg(1)-O(4) bond length is 2.14 Å. The Mg(1)-O(5) bond length is 2.19 Å. The Mg(1)-O(6) bond length is 2.17 Å. There are five inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to one O(12), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted TbO7 pentagonal bipyramids that share  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 Tb(1)-O(12) bond length is 2.56 Å. The Tb(1)-O(3) bond length is 2.29 Å. The Tb(1)-O(4) bond length is 2.30 Å. The Tb(1)-O(5) bond length is 2.33 Å. The Tb(1)-O(6) bond length is 2.35 Å. The Tb(1)-O(7) bond length is 2.36 Å. The Tb(1)-O(8) bond length is 2.35 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 2.35 Å. The Tb(2)-O(11) bond length is 2.44 Å. The Tb(2)-O(2) bond length is 2.30 Å. The Tb(2)-O(5) bond length is 2.40 Å. The Tb(2)-O(6) bond length is 2.45 Å. The Tb(2)-O(7) bond length is 2.38 Å. The Tb(2)-O(8) bond length is 2.38 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 2.33 Å. The Tb(3)-O(11) bond length is 2.33 Å. The Tb(3)-O(2) bond length is 2.28 Å. The Tb(3)-O(3) bond length is 2.93 Å. The Tb(3)-O(4) bond length is 2.90 Å. The Tb(3)-O(5) bond length is 2.43 Å. The Tb(3)-O(6) bond length is 2.48 Å. In the fourth Tb site, Tb(4) is bonded in a 7-coordinate geometry to one O(1), one O(12), one O(2), one O(3), one O(4), one O(7), and one O(8) atom. The Tb(4)-O(1) bond length is 2.40 Å. The Tb(4)-O(12) bond length is 2.29 Å. The Tb(4)-O(2) bond length is 2.35 Å. The Tb(4)-O(3) bond length is 2.34 Å. The Tb(4)-O(4) bond length is 2.41 Å. The Tb(4)-O(7) bond length is 2.46 Å. The Tb(4)-O(8) bond length is 2.45 Å. In the fifth Tb site, Tb(5) is bonded in a 6-coordinate geometry to one O(10), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. The Tb(5)-O(10) bond length is 2.32 Å. The Tb(5)-O(5) bond length is 2.79 Å. The Tb(5)-O(6) bond length is 2.55 Å. The Tb(5)-O(7) bond length is 2.19 Å. The Tb(5)-O(8) bond length is 2.26 Å. The Tb(5)-O(9) bond length is 2.20 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 edges with two equivalent Mo(2)O6 octahedra,  an edgeedge with one Tb(1)O7 pentagonal bipyramid, and  an edgeedge with one Mg(1)O5 square pyramid. The Mo(1)-O(1) bond length is 2.07 Å. The Mo(1)-O(10) bond length is 2.13 Å. The Mo(1)-O(11) bond length is 2.13 Å. The Mo(1)-O(12) bond length is 2.06 Å. The Mo(1)-O(4) bond length is 2.07 Å. The Mo(1)-O(9) bond length is 1.99 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 edges with two equivalent Mo(1)O6 octahedra,  an edgeedge with one Tb(1)O7 pentagonal bipyramid, and  an edgeedge with one Mg(1)O5 square pyramid. The Mo(2)-O(10) bond length is 2.15 Å. The Mo(2)-O(11) bond length is 2.16 Å. The Mo(2)-O(12) bond length is 2.14 Å. The Mo(2)-O(2) bond length is 2.18 Å. The Mo(2)-O(3) bond length is 2.15 Å. The Mo(2)-O(9) bond length is 2.10 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Tb(2), one Tb(3), one Tb(4), and one Mo(1) atom to form OTb3Mo tetrahedra that share  a cornercorner with one O(2)Tb3Mo tetrahedra, corners with two equivalent O(7)Tb4 tetrahedra, corners with two equivalent O(8)Tb4 tetrahedra, corners with two equivalent O(6)Tb4Mg trigonal bipyramids, and  an edgeedge with one O(2)Tb3Mo tetrahedra. In the second O site, O(2) is bonded to one Tb(2), one Tb(3), one Tb(4), and one Mo(2) atom to form OTb3Mo tetrahedra that share  a cornercorner with one O(1)Tb3Mo tetrahedra, corners with two equivalent O(7)Tb4 tetrahedra, corners with two equivalent O(8)Tb4 tetrahedra,  an edgeedge with one O(1)Tb3Mo tetrahedra, and  an edgeedge with one O(6)Tb4Mg trigonal bipyramid. 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 in a 5-coordinate geometry to one Mg(1), one Tb(1), one Tb(3), one Tb(4), and one Mo(1) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(1), one Tb(1), one Tb(2), one Tb(3), and one Tb(5) atom. In the sixth O site, O(6) is bonded to one Mg(1), one Tb(1), one Tb(2), one Tb(3), and one Tb(5) atom to form distorted OTb4Mg trigonal bipyramids that share  a cornercorner with one O(8)Tb4 tetrahedra, corners with two equivalent O(1)Tb3Mo tetrahedra, corners with three equivalent O(7)Tb4 tetrahedra,  an edgeedge with one O(2)Tb3Mo tetrahedra, and  an edgeedge with one O(8)Tb4 tetrahedra. 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 distorted OTb4 tetrahedra that share corners with two equivalent O(1)Tb3Mo tetrahedra, corners with two equivalent O(2)Tb3Mo tetrahedra, corners with three equivalent O(6)Tb4Mg trigonal bipyramids, 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(1)Tb3Mo tetrahedra, corners with two equivalent O(2)Tb3Mo tetrahedra,  a cornercorner with one O(6)Tb4Mg trigonal bipyramid, edges with two equivalent O(7)Tb4 tetrahedra, and  an edgeedge with one O(6)Tb4Mg trigonal bipyramid. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Tb(5), one Mo(1), and one Mo(2) atom. In the tenth O site, O(10) 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 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 in a rectangular see-saw-like geometry to one Tb(1), one Tb(4), one Mo(1), and one Mo(2) atom.