Mg2C5N2H2O5 crystallizes in the tetragonal P4_12_12 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one N(1), one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted MgNO5 octahedra that share corners with two equivalent Mg(2)O6 octahedra and edges with two equivalent Mg(1)NO5 octahedra. The corner-sharing octahedral tilt angles range from 52-63°. The Mg(1)-N(1) bond length is 2.16 Å. The Mg(1)-O(1) bond length is 2.11 Å. There is one shorter (2.03 Å) and one longer (2.08 Å) Mg(1)-O(2) bond length. There is one shorter (2.05 Å) and one longer (2.15 Å) Mg(1)-O(4) bond length. In the second Mg site, Mg(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form distorted corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 52-63°. Both Mg(2)-O(2) bond lengths are 2.02 Å. Both Mg(2)-O(3) bond lengths are 2.12 Å. Both Mg(2)-O(5) bond lengths are 2.15 Å. In the third Mg site, Mg(3) is bonded in a distorted square co-planar geometry to two equivalent N(2) and two equivalent O(3) atoms. Both Mg(3)-N(2) bond lengths are 2.07 Å. Both Mg(3)-O(3) bond lengths are 2.04 Å. There are five inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one C(4), one O(1), and one O(3) atom. The C(1)-C(4) bond length is 1.48 Å. The C(1)-O(1) bond length is 1.24 Å. The C(1)-O(3) bond length is 1.28 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one O(4) and one O(5) atom. The C(2)-O(4) bond length is 1.28 Å. The C(2)-O(5) bond length is 1.25 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to one N(1) atom. The C(3)-N(1) bond length is 1.36 Å. In the fourth C site, C(4) is bonded in a distorted single-bond geometry to one C(1), one C(5), and one N(2) atom. The C(4)-C(5) bond length is 1.39 Å. The C(4)-N(2) bond length is 1.36 Å. In the fifth C site, C(5) is bonded in a distorted single-bond geometry to one C(4) and one H(2) atom. The C(5)-H(2) bond length is 0.96 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded in a 3-coordinate geometry to one Mg(1), one C(3), and one N(2) atom. The N(1)-N(2) bond length is 1.33 Å. In the second N site, N(2) is bonded in a distorted trigonal planar geometry to one Mg(3), one C(4), and one N(1) atom. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(2) atom. The H(1)-O(2) bond length is 0.79 Å. In the second H site, H(2) is bonded in a single-bond geometry to one C(5) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Mg(1) and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Mg(2), two equivalent Mg(1), and one H(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(2), one Mg(3), and one C(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one C(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Mg(2) and one C(2) atom. Linkers: 4 [O]C(=O)C1=CC(C([O])=O)=N[N]1 ,4 [O]C(=O)C1=NN=C(C([O])=O)[CH]1. Metal clusters: 16 [Mg]. The MOF has largest included sphere 5.31 A, density 1.50 g/cm3, surface area 3128.15 m2/g, accessible volume 0.22 cm3/g