MgC5H5O4 crystallizes in the triclinic P-1 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), one O(10), one O(2), one O(6), one O(8), and one O(9) atom to form MgO6 octahedra that share  a cornercorner with one C(13,15)H3O tetrahedra;  an edgeedge with one Mg(2)O6 octahedra; and  an edgeedge with one Mg(3)O6 octahedra. The Mg(1)-O(1) bond length is 2.10 Å. The Mg(1)-O(10) bond length is 2.15 Å. The Mg(1)-O(2) bond length is 2.12 Å. The Mg(1)-O(6) bond length is 2.04 Å. The Mg(1)-O(8) bond length is 2.02 Å. The Mg(1)-O(9) bond length is 2.04 Å. In the second Mg site, Mg(2) is bonded to one O(11), one O(2), one O(3), one O(4), one O(7), and one O(9) atom to form MgO6 octahedra that share  a cornercorner with one C(14)H3O tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Mg(3)O6 octahedra. The Mg(2)-O(11) bond length is 2.15 Å. The Mg(2)-O(2) bond length is 2.10 Å. The Mg(2)-O(3) bond length is 2.12 Å. The Mg(2)-O(4) bond length is 2.04 Å. The Mg(2)-O(7) bond length is 2.04 Å. The Mg(2)-O(9) bond length is 2.02 Å. In the third Mg site, Mg(3) is bonded to one O(1), one O(12), one O(3), one O(5), one O(7), and one O(8) atom to form MgO6 octahedra that share  a cornercorner with one C(13,15)H3O tetrahedra;  an edgeedge with one Mg(1)O6 octahedra; and  an edgeedge with one Mg(2)O6 octahedra. The Mg(3)-O(1) bond length is 2.12 Å. The Mg(3)-O(12) bond length is 2.15 Å. The Mg(3)-O(3) bond length is 2.10 Å. The Mg(3)-O(5) bond length is 2.04 Å. The Mg(3)-O(7) bond length is 2.02 Å. The Mg(3)-O(8) bond length is 2.04 Å. There are thirteen 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(4) atom. The C(1)-C(4) bond length is 1.49 Å. The C(1)-O(1) bond length is 1.29 Å. The C(1)-O(4) bond length is 1.27 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one C(5), one O(2), and one O(5) atom. The C(2)-C(5) bond length is 1.49 Å. The C(2)-O(2) bond length is 1.29 Å. The C(2)-O(5) bond length is 1.27 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to one C(6), one O(3), and one O(6) atom. The C(3)-C(6) bond length is 1.49 Å. The C(3)-O(3) bond length is 1.29 Å. The C(3)-O(6) bond length is 1.27 Å. In the fourth C site, C(4) is bonded in a trigonal planar geometry to one C(1); one C(10); and one C(7,9) atom. The C(4)-C(10) bond length is 1.44 Å. The C(4)-C(7,9) bond length is 1.40 Å. In the fifth C site, C(5) is bonded in a trigonal planar geometry to one C(11), one C(2), and one C(8) atom. The C(5)-C(11) bond length is 1.44 Å. The C(5)-C(8) bond length is 1.40 Å. In the sixth C site, C(6) is bonded in a trigonal planar geometry to one C(12); one C(3); and one C(7,9) atom. The C(6)-C(12) bond length is 1.44 Å. The C(6)-C(7,9) bond length is 1.40 Å. In the seventh C site, C(7,9) is bonded in a distorted trigonal planar geometry to one C(10); one C(4); and one H(1,3) atom. The C(7,9)-C(10) bond length is 1.40 Å. The C(7,9)-H(1,3) bond length is 1.09 Å. In the eighth C site, C(8) is bonded in a distorted trigonal planar geometry to one C(11), one C(5), and one H(2) atom. The C(8)-C(11) bond length is 1.40 Å. The C(8)-H(2) bond length is 1.09 Å. In the ninth C site, C(10) is bonded in a distorted single-bond geometry to one C(4); one C(7,9); and one O(7) atom. The C(10)-O(7) bond length is 1.34 Å. In the tenth C site, C(11) is bonded in a distorted single-bond geometry to one C(5), one C(8), and one O(8) atom. The C(11)-O(8) bond length is 1.34 Å. In the eleventh C site, C(12) is bonded in a distorted single-bond geometry to one C(6); one C(7,9); and one O(9) atom. The C(12)-C(7,9) bond length is 1.40 Å. The C(12)-O(9) bond length is 1.34 Å. In the twelfth C site, C(13,15) is bonded to one H(10,12); one H(4,6); one H(7,9); and one O(10) atom to form CH3O tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. The C(13,15)-H(10,12) bond length is 1.10 Å. The C(13,15)-H(4,6) bond length is 1.10 Å. The C(13,15)-H(7,9) bond length is 1.10 Å. The C(13,15)-O(10) bond length is 1.45 Å. In the thirteenth C site, C(14) is bonded to one H(11), one H(5), one H(8), and one O(11) atom to form CH3O tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. The C(14)-H(11) bond length is 1.10 Å. The C(14)-H(5) bond length is 1.10 Å. The C(14)-H(8) bond length is 1.10 Å. The C(14)-O(11) bond length is 1.45 Å. There are ten inequivalent H sites. In the first H site, H(1,3) is bonded in a single-bond geometry to one C(7,9) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(8) atom. In the third H site, H(4,6) is bonded in a single-bond geometry to one C(13,15) atom. In the fourth H site, H(5) is bonded in a single-bond geometry to one C(14) atom. In the fifth H site, H(7,9) is bonded in a single-bond geometry to one C(13,15) atom. In the sixth H site, H(8) is bonded in a single-bond geometry to one C(14) atom. In the seventh H site, H(10,12) is bonded in a single-bond geometry to one C(13,15) atom. In the eighth H site, H(11) is bonded in a single-bond geometry to one C(14) atom. In the ninth H site, H(13,15) is bonded in a single-bond geometry to one O(10) atom. The H(13,15)-O(10) bond length is 0.97 Å. In the tenth H site, H(14) is bonded in a single-bond geometry to one O(11) atom. The H(14)-O(11) bond length is 0.97 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(3), and one C(1) 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(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(2), one Mg(3), and one C(3) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Mg(2) and one C(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Mg(3) and one C(2) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Mg(1) and one C(3) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Mg(2), one Mg(3), and one C(10) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(3), and one C(11) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one C(12) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1); one C(13,15); and one H(13,15) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal non-coplanar geometry to one Mg(2), one C(14), and one H(14) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal non-coplanar geometry to one Mg(3); one C(13,15); and one H(13,15) atom. The O(12)-C(13,15) bond length is 1.45 Å. The O(12)-H(13,15) bond length is 0.97 Å. Linkers: 2 [O][C]c1cc([O])c(C([O])=O)cc1[O] ,3 [O]C(=O)c1cc([O])c(C([O])=O)cc1[O]. Metal clusters: 6 [Mg]. The MOF has largest included sphere 7.59 A, density 1.14 g/cm3, surface area 3999.33 m2/g, accessible volume 0.47 cm3/g