MgNd2Cr2O8 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form distorted MgO4 trigonal pyramids that share corners with two equivalent Cr(2)O4 tetrahedra and  an edgeedge with one Cr(1)O4 trigonal pyramid. There are two inequivalent Nd sites. In the first Nd site, Nd(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 Nd site, Nd(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 Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form distorted CrO4 trigonal pyramids that share  an edgeedge with one Mg(1)O4 trigonal pyramid. In the second Cr site, Cr(2) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form CrO4 tetrahedra that share corners with two equivalent Mg(1)O4 trigonal pyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Nd(1), one Nd(2), and one Cr(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nd(1), one Nd(2), and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to one Mg(1), one Nd(1), one Nd(2), and one Cr(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Nd(1), one Nd(2), and one Cr(2) atom.
MgNd2Cr2O8 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form distorted MgO4 trigonal pyramids that share corners with two equivalent Cr(2)O4 tetrahedra and  an edgeedge with one Cr(1)O4 trigonal pyramid. Both Mg(1)-O(1) bond lengths are 1.98 Å. Both Mg(1)-O(3) bond lengths are 2.00 Å. There are two inequivalent Nd sites. In the first Nd site, Nd(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 Nd(1)-O(1) bond lengths are 2.57 Å. Both Nd(1)-O(2) bond lengths are 2.42 Å. Both Nd(1)-O(3) bond lengths are 2.56 Å. Both Nd(1)-O(4) bond lengths are 2.44 Å. In the second Nd site, Nd(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 Nd(2)-O(1) bond lengths are 2.63 Å. Both Nd(2)-O(2) bond lengths are 2.59 Å. Both Nd(2)-O(3) bond lengths are 2.47 Å. Both Nd(2)-O(4) bond lengths are 2.36 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form distorted CrO4 trigonal pyramids that share  an edgeedge with one Mg(1)O4 trigonal pyramid. Both Cr(1)-O(2) bond lengths are 1.77 Å. Both Cr(1)-O(3) bond lengths are 1.87 Å. In the second Cr site, Cr(2) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form CrO4 tetrahedra that share corners with two equivalent Mg(1)O4 trigonal pyramids. Both Cr(2)-O(1) bond lengths are 1.83 Å. Both Cr(2)-O(4) bond lengths are 1.78 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Nd(1), one Nd(2), and one Cr(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nd(1), one Nd(2), and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to one Mg(1), one Nd(1), one Nd(2), and one Cr(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Nd(1), one Nd(2), and one Cr(2) atom.