MgGd2Mo2(O4Cl)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent Cl(1) atoms to form MgCl2O4 octahedra that share edges with two equivalent Mo(1)O4 trigonal pyramids. Gd(1) is bonded in a 7-coordinate geometry to one O(1), one O(4), two equivalent O(2), two equivalent O(3), and one Cl(1) atom. Mo(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form MoO4 trigonal pyramids that share  an edgeedge with one Mg(1)Cl2O4 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Gd(1) and one Mo(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Gd(1) and one Mo(1) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Gd(1), and one Mo(1) atom. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Mg(1), one Gd(1), and one Mo(1) atom. Cl(1) is bonded in a distorted single-bond geometry to one Mg(1) and one Gd(1) atom.
MgGd2Mo2(O4Cl)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent Cl(1) atoms to form MgCl2O4 octahedra that share edges with two equivalent Mo(1)O4 trigonal pyramids. Both Mg(1)-O(3) bond lengths are 2.08 Å. Both Mg(1)-O(4) bond lengths are 2.16 Å. Both Mg(1)-Cl(1) bond lengths are 2.46 Å. Gd(1) is bonded in a 7-coordinate geometry to one O(1), one O(4), two equivalent O(2), two equivalent O(3), and one Cl(1) atom. The Gd(1)-O(1) bond length is 2.30 Å. The Gd(1)-O(4) bond length is 2.25 Å. There is one shorter (2.33 Å) and one longer (2.48 Å) Gd(1)-O(2) bond length. There is one shorter (2.33 Å) and one longer (2.59 Å) Gd(1)-O(3) bond length. The Gd(1)-Cl(1) bond length is 2.95 Å. Mo(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form MoO4 trigonal pyramids that share  an edgeedge with one Mg(1)Cl2O4 octahedra. The Mo(1)-O(1) bond length is 1.80 Å. The Mo(1)-O(2) bond length is 1.85 Å. The Mo(1)-O(3) bond length is 1.95 Å. The Mo(1)-O(4) bond length is 1.90 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Gd(1) and one Mo(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Gd(1) and one Mo(1) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Gd(1), and one Mo(1) atom. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Mg(1), one Gd(1), and one Mo(1) atom. Cl(1) is bonded in a distorted single-bond geometry to one Mg(1) and one Gd(1) atom.