MgH20(C9O2)4 crystallizes in the cubic Im-3 space group. The structure consists of a MgH20(C9O2)4 framework. Mg(1) is bonded in a square co-planar geometry to four equivalent O(1) atoms. All Mg(1)-O(1) bond lengths are 2.05 Å. There are nine inequivalent C sites. In the first C site, C(5) is bonded in a trigonal planar geometry to one C(4), one C(6), and one C(8) atom. The C(5)-C(4) bond length is 1.40 Å. The C(5)-C(6) bond length is 1.35 Å. The C(5)-C(8) bond length is 1.49 Å. In the second C site, C(6) is bonded in a distorted single-bond geometry to one C(5) and one H(3) atom. The C(6)-H(3) bond length is 0.93 Å. In the third C site, C(7) is bonded in a distorted single-bond geometry to one C(2) and one H(4) atom. The C(7)-C(2) bond length is 1.39 Å. The C(7)-H(4) bond length is 0.93 Å. In the fourth C site, C(8) is bonded in a trigonal planar geometry to one C(5) and two equivalent C(9) atoms. There is one shorter (1.39 Å) and one longer (1.41 Å) C(8)-C(9) bond length. In the fifth C site, C(9) is bonded in a single-bond geometry to two equivalent C(8) and one H(5) atom. The C(9)-H(5) bond length is 0.93 Å. In the sixth C site, C(1) is bonded in a bent 120 degrees geometry to one C(2), one O(1), and one O(2) atom. The C(1)-C(2) bond length is 1.49 Å. The C(1)-O(1) bond length is 1.25 Å. The C(1)-O(2) bond length is 1.24 Å. In the seventh C site, C(2) is bonded in a trigonal planar geometry to one C(1), one C(3), and one C(7) atom. The C(2)-C(3) bond length is 1.40 Å. In the eighth C site, C(3) is bonded in a distorted single-bond geometry to one C(2), one C(4), and one H(1) atom. The C(3)-C(4) bond length is 1.35 Å. The C(3)-H(1) bond length is 0.93 Å. In the ninth C site, C(4) is bonded in a distorted trigonal planar geometry to one C(3), one C(5), and one H(2) atom. The C(4)-H(2) bond length is 0.93 Å. There are five inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(3) 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(6) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(7) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(9) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one C(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one C(1) atom. Linkers: 16 [O]C(=O)c1ccc(-c2cc(-c3ccc(C([O])=O)cc3)cc(-c3ccc(C([O])=O)cc3)c2)cc1. Metal clusters: 12 O=[C]O[Mg]O[C]=O.[O][C]=O.[O][C]=O. RCSR code: pto. The MOF has largest included sphere 16.80 A, density 0.59 g/cm3, surface area 5414.10 m2/g, accessible volume 1.29 cm3/g