MgC7H4O5 crystallizes in the monoclinic C2 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(4), one O(5), one O(7), and one O(8) atom to form distorted corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 57°. The Mg(1)-O(1) bond length is 2.31 Å. The Mg(1)-O(2) bond length is 2.31 Å. The Mg(1)-O(4) bond length is 2.01 Å. The Mg(1)-O(5) bond length is 2.01 Å. The Mg(1)-O(7) bond length is 1.99 Å. The Mg(1)-O(8) bond length is 1.99 Å. In the second Mg site, Mg(2) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(8) atoms to form distorted corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 57°. Both Mg(2)-O(3) bond lengths are 2.32 Å. Both Mg(2)-O(6) bond lengths are 2.01 Å. Both Mg(2)-O(8) bond lengths are 1.99 Å. There are eleven inequivalent C sites. In the first C site, C(1) is bonded in a distorted single-bond geometry to two equivalent C(8) and one O(7) atom. Both C(1)-C(8) bond lengths are 1.41 Å. The C(1)-O(7) bond length is 1.33 Å. In the second C site, C(2) is bonded in a distorted single-bond geometry to two equivalent C(9,10) and one O(8) atom. Both C(2)-C(9,10) bond lengths are 1.41 Å. The C(2)-O(8) bond length is 1.33 Å. In the third C site, C(3) is bonded in a distorted trigonal planar geometry to one C(11), one C(8), and one H(4) atom. The C(3)-C(11) bond length is 1.41 Å. The C(3)-C(8) bond length is 1.39 Å. The C(3)-H(4) bond length is 1.09 Å. In the fourth C site, C(4) is bonded in a distorted trigonal planar geometry to one C(12); one C(9,10); and one H(5,6) atom. The C(4)-C(12) bond length is 1.41 Å. The C(4)-C(9,10) bond length is 1.39 Å. The C(4)-H(5,6) bond length is 1.09 Å. In the fifth C site, C(5) is bonded in a distorted trigonal planar geometry to one C(12); one C(9,10); and one H(5,6) atom. The C(5)-C(12) bond length is 1.41 Å. The C(5)-C(9,10) bond length is 1.39 Å. The C(5)-H(5,6) bond length is 1.09 Å. In the sixth C site, C(6) is bonded in a distorted bent 120 degrees geometry to one C(11) and two equivalent O(4) atoms. The C(6)-C(11) bond length is 1.49 Å. Both C(6)-O(4) bond lengths are 1.28 Å. In the seventh C site, C(7) is bonded in a distorted bent 120 degrees geometry to one C(12), one O(5), and one O(6) atom. The C(7)-C(12) bond length is 1.49 Å. The C(7)-O(5) bond length is 1.28 Å. The C(7)-O(6) bond length is 1.28 Å. In the eighth C site, C(8) is bonded in a distorted single-bond geometry to one C(1), one C(3), and one O(1) atom. The C(8)-O(1) bond length is 1.39 Å. In the ninth C site, C(9,10) is bonded in a distorted single-bond geometry to one C(2), one C(4), and one O(2) atom. The C(9,10)-O(2) bond length is 1.39 Å. In the tenth C site, C(11) is bonded in a trigonal planar geometry to one C(6) and two equivalent C(3) atoms. In the eleventh C site, C(12) is bonded in a trigonal planar geometry to one C(4), one C(5), and one C(7) atom. There are four inequivalent H sites. In the first H site, H(1,3) is bonded in a single-bond geometry to one O(1) atom. The H(1,3)-O(1) bond length is 0.97 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(2) atom. The H(2)-O(2) bond length is 0.97 Å. In the third H site, H(4) is bonded in a single-bond geometry to one C(3) atom. In the fourth H site, H(5,6) is bonded in a single-bond geometry to one C(4) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1); one C(8); and one H(1,3) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1); one C(9,10); and one H(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Mg(2); one C(9,10); and one H(1,3) atom. The O(3)-C(9,10) bond length is 1.39 Å. The O(3)-H(1,3) bond length is 0.97 Å. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Mg(1) and one C(6) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Mg(1) and one C(7) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Mg(2) and one C(7) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to two equivalent Mg(1) and one C(1) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Mg(1), one Mg(2), and one C(2) atom. Linkers: 3 [O]C(=O)c1cc(O)c([O])c(O)c1. Metal clusters: 3 [Mg]. RCSR code: pth. The MOF has largest included sphere 3.56 A, density 1.30 g/cm3, surface area 4152.79 m2/g, accessible volume 0.33 cm3/g