MgH2(C3O2)2 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form face-sharing MgO6 octahedra. The Mg(1)-O(1) bond length is 1.99 Å. The Mg(1)-O(2) bond length is 2.17 Å. The Mg(1)-O(3) bond length is 1.99 Å. The Mg(1)-O(4) bond length is 2.18 Å. The Mg(1)-O(5) bond length is 1.99 Å. The Mg(1)-O(6) bond length is 2.18 Å. In the second Mg site, Mg(2) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form face-sharing MgO6 octahedra. Both Mg(2)-O(2) bond lengths are 2.07 Å. Both Mg(2)-O(4) bond lengths are 2.07 Å. Both Mg(2)-O(6) bond lengths are 2.07 Å. There are eight inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one C(7) and two equivalent C(2,6) atoms. The C(1)-C(7) bond length is 1.50 Å. Both C(1)-C(2,6) bond lengths are 1.40 Å. In the second C site, C(2,6) is bonded in a distorted single-bond geometry to one C(1), one C(3), and one H(1) atom. The C(2,6)-C(3) bond length is 1.40 Å. The C(2,6)-H(1) bond length is 1.09 Å. In the third C site, C(3) is bonded in a trigonal planar geometry to one C(2,6); one C(4); and one C(8) atom. The C(3)-C(4) bond length is 1.40 Å. The C(3)-C(8) bond length is 1.50 Å. In the fourth C site, C(4) is bonded in a distorted single-bond geometry to one C(3), one C(5), and one H(2) atom. The C(4)-C(5) bond length is 1.40 Å. The C(4)-H(2) bond length is 1.09 Å. In the fifth C site, C(5) is bonded in a trigonal planar geometry to one C(2,6); one C(4); and one C(9) atom. The C(5)-C(2,6) bond length is 1.40 Å. The C(5)-C(9) bond length is 1.50 Å. In the sixth C site, C(7) is bonded in a distorted bent 120 degrees geometry to one C(1), one O(1), and one O(2) atom. The C(7)-O(1) bond length is 1.25 Å. The C(7)-O(2) bond length is 1.29 Å. In the seventh C site, C(8) is bonded in a distorted bent 120 degrees geometry to one C(3), one O(3), and one O(4) atom. The C(8)-O(3) bond length is 1.25 Å. The C(8)-O(4) bond length is 1.29 Å. In the eighth C site, C(9) is bonded in a distorted bent 120 degrees geometry to one C(5), one O(5), and one O(6) atom. The C(9)-O(5) bond length is 1.25 Å. The C(9)-O(6) bond length is 1.29 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(2,6) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(4) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(2,6) atom. The H(3)-C(2,6) bond length is 1.09 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Mg(1) and one C(7) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(2), and one C(7) atom. In the third O site, O(3) is bonded in a linear geometry to one Mg(1) and one C(8) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(2), and one C(8) atom. In the fifth O site, O(5) is bonded in a linear geometry to one Mg(1) and one C(9) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(2), and one C(9) atom. Linkers: 2 [O]C(=O)c1cc(C([O])=O)cc(C([O])=O)c1. Metal clusters: 3 [Mg]. The MOF has largest included sphere 1.41 A, density 2.13 g/cm3, surface area 2892.84 m2/g, accessible volume 0.04 cm3/g