MgMoH2O5 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form MgO6 octahedra that share corners with five equivalent Mo(1)O4 tetrahedra and  an edgeedge with one Mg(1)O6 octahedra. Mo(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form MoO4 tetrahedra that share corners with five equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 19-58°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(5) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(5) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one Mo(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one Mo(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one H(1), and one H(2) atom.
MgMoH2O5 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form MgO6 octahedra that share corners with five equivalent Mo(1)O4 tetrahedra and  an edgeedge with one Mg(1)O6 octahedra. The Mg(1)-O(2) bond length is 2.06 Å. The Mg(1)-O(3) bond length is 2.04 Å. The Mg(1)-O(4) bond length is 2.08 Å. The Mg(1)-O(5) bond length is 2.07 Å. There is one shorter (2.08 Å) and one longer (2.13 Å) Mg(1)-O(1) bond length. Mo(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form MoO4 tetrahedra that share corners with five equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 19-58°. The Mo(1)-O(1) bond length is 1.80 Å. The Mo(1)-O(2) bond length is 1.76 Å. The Mo(1)-O(3) bond length is 1.73 Å. The Mo(1)-O(4) bond length is 1.78 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(5) atom. The H(1)-O(5) bond length is 0.98 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(5) atom. The H(2)-O(5) bond length is 0.97 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one Mo(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one Mo(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one H(1), and one H(2) atom.