Mg3H6(C9O8)2 crystallizes in the trigonal R32 space group. Mg(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form corner-sharing MgO5 square pyramids. The Mg(1)-O(4) bond length is 2.02 Å. Both Mg(1)-O(1) bond lengths are 2.10 Å. Both Mg(1)-O(2) bond lengths are 2.07 Å. There are three inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one C(2), one O(1), and one O(2) atom. The C(1)-C(2) bond length is 1.50 Å. The C(1)-O(1) bond length is 1.24 Å. The C(1)-O(2) bond length is 1.22 Å. In the second C site, C(2) is bonded in a distorted single-bond geometry to one C(1), one C(3), and one O(3) atom. The C(2)-C(3) bond length is 1.38 Å. The C(2)-O(3) bond length is 1.35 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to one C(2) and one H(1) atom. The C(3)-H(1) bond length is 0.93 Å. H(1) is bonded in a single-bond geometry to one C(3) atom. There are four inequivalent O sites. In the first O site, O(4) is bonded in a trigonal planar geometry to three equivalent Mg(1) atoms. In the second O site, O(1) is bonded in a bent 120 degrees geometry to one Mg(1) and one C(1) atom. In the third O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one C(1) atom. In the fourth O site, O(3) is bonded in a water-like geometry to two equivalent C(2) atoms. Linkers: 9 [O]C(=O)c1ccc(C([O])=O)o1. Metal clusters: 2 O=[C]O[Mg].O=[C]O[Mg]O[Mg]O[C]=O.[O][C]=O.[O][C]=O.[O][C]=O ,1 O=[C]O[Mg]O[C]=O.O=[C]O[Mg]O[Mg]O[C]=O.[O][C]=O.[O][C]=O. RCSR code: pcu. The MOF has largest included sphere 7.18 A, density 0.74 g/cm3, surface area 4210.61 m2/g, accessible volume 0.97 cm3/g