MgTb2V2O8 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with two equivalent V(1)O4 tetrahedra and  an edgeedge with one V(2)O4 trigonal pyramid. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Tb site, Tb(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent V sites. In the first V site, V(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form VO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra. In the second V site, V(2) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form distorted VO4 trigonal pyramids that share  an edgeedge with one Mg(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Tb(1), one Tb(2), and one V(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Tb(1), one Tb(2), and one V(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Tb(1), one Tb(2), and one V(1) atom. In the fourth O site, O(4) is bonded in a distorted see-saw-like geometry to one Mg(1), one Tb(1), one Tb(2), and one V(2) atom.
MgTb2V2O8 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with two equivalent V(1)O4 tetrahedra and  an edgeedge with one V(2)O4 trigonal pyramid. Both Mg(1)-O(3) bond lengths are 1.95 Å. Both Mg(1)-O(4) bond lengths are 1.98 Å. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Tb(1)-O(1) bond lengths are 2.56 Å. Both Tb(1)-O(2) bond lengths are 2.26 Å. Both Tb(1)-O(3) bond lengths are 2.54 Å. Both Tb(1)-O(4) bond lengths are 2.43 Å. In the second Tb site, Tb(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Tb(2)-O(1) bond lengths are 2.34 Å. Both Tb(2)-O(2) bond lengths are 2.38 Å. Both Tb(2)-O(3) bond lengths are 2.57 Å. Both Tb(2)-O(4) bond lengths are 2.44 Å. There are two inequivalent V sites. In the first V site, V(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form VO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra. Both V(1)-O(2) bond lengths are 1.80 Å. Both V(1)-O(3) bond lengths are 1.83 Å. In the second V site, V(2) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form distorted VO4 trigonal pyramids that share  an edgeedge with one Mg(1)O4 tetrahedra. Both V(2)-O(1) bond lengths are 1.77 Å. Both V(2)-O(4) bond lengths are 1.91 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Tb(1), one Tb(2), and one V(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Tb(1), one Tb(2), and one V(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Tb(1), one Tb(2), and one V(1) atom. In the fourth O site, O(4) is bonded in a distorted see-saw-like geometry to one Mg(1), one Tb(1), one Tb(2), and one V(2) atom.