MgC4HO3 crystallizes in the triclinic P1 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), one O(3), one O(5), one O(6), and one O(8) atom to form edge-sharing MgO5 square pyramids. The Mg(1)-O(1) bond length is 2.02 Å. The Mg(1)-O(3) bond length is 2.11 Å. The Mg(1)-O(5) bond length is 2.07 Å. The Mg(1)-O(6) bond length is 1.97 Å. The Mg(1)-O(8) bond length is 2.17 Å. In the second Mg site, Mg(2) is bonded to one O(2), one O(4), one O(6), one O(8), and one O(9) atom to form edge-sharing MgO5 square pyramids. The Mg(2)-O(2) bond length is 2.17 Å. The Mg(2)-O(4) bond length is 2.02 Å. The Mg(2)-O(6) bond length is 2.11 Å. The Mg(2)-O(8) bond length is 2.07 Å. The Mg(2)-O(9) bond length is 1.97 Å. In the third Mg site, Mg(3) is bonded to one O(2), one O(3), one O(5), one O(7), and one O(9) atom to form edge-sharing MgO5 square pyramids. The Mg(3)-O(2) bond length is 2.07 Å. The Mg(3)-O(3) bond length is 1.97 Å. The Mg(3)-O(5) bond length is 2.17 Å. The Mg(3)-O(7) bond length is 2.02 Å. The Mg(3)-O(9) bond length is 2.11 Å. In the fourth Mg site, Mg(4) is bonded to one O(10,13); one O(12); one O(14); one O(15); and one O(17) atom to form edge-sharing MgO5 square pyramids. The Mg(4)-O(10,13) bond length is 2.02 Å. The Mg(4)-O(12) bond length is 2.11 Å. The Mg(4)-O(14) bond length is 2.07 Å. The Mg(4)-O(15) bond length is 1.97 Å. The Mg(4)-O(17) bond length is 2.17 Å. In the fifth Mg site, Mg(5) is bonded to one O(10,13); one O(11); one O(15); one O(17); and one O(18) atom to form edge-sharing MgO5 square pyramids. The Mg(5)-O(10,13) bond length is 2.02 Å. The Mg(5)-O(11) bond length is 2.17 Å. The Mg(5)-O(15) bond length is 2.11 Å. The Mg(5)-O(17) bond length is 2.07 Å. The Mg(5)-O(18) bond length is 1.97 Å. In the sixth Mg site, Mg(6) is bonded to one O(11), one O(12), one O(14), one O(16), and one O(18) atom to form edge-sharing MgO5 square pyramids. The Mg(6)-O(11) bond length is 2.07 Å. The Mg(6)-O(12) bond length is 1.97 Å. The Mg(6)-O(14) bond length is 2.17 Å. The Mg(6)-O(16) bond length is 2.02 Å. The Mg(6)-O(18) bond length is 2.11 Å. There are twenty-two 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 1.54 Å. The C(1)-O(1) bond length is 1.31 Å. The C(1)-O(2) bond length is 1.24 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one C(1), one C(3), and one C(4) atom. The C(2)-C(3) bond length is 1.51 Å. The C(2)-C(4) bond length is 1.31 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 1.14 Å. In the fourth C site, C(4) is bonded in a single-bond geometry to one C(15,19); one C(2); and one O(3) atom. The C(4)-C(15,19) bond length is 1.43 Å. The C(4)-O(3) bond length is 1.39 Å. In the fifth C site, C(5) is bonded in a distorted bent 120 degrees geometry to one C(6), one O(4), and one O(5) atom. The C(5)-C(6) bond length is 1.54 Å. The C(5)-O(4) bond length is 1.31 Å. The C(5)-O(5) bond length is 1.24 Å. In the sixth C site, C(6) is bonded in a trigonal planar geometry to one C(5), one C(7), and one C(8) atom. The C(6)-C(7) bond length is 1.51 Å. The C(6)-C(8) bond length is 1.31 Å. In the seventh C site, C(7) is bonded in a distorted single-bond geometry to one C(20), one C(6), and one H(2) atom. The C(7)-C(20) bond length is 1.43 Å. The C(7)-H(2) bond length is 1.14 Å. In the eighth C site, C(8) is bonded in a single-bond geometry to one C(15,19); one C(6); and one O(6) atom. The C(8)-C(15,19) bond length is 1.43 Å. The C(8)-O(6) bond length is 1.39 Å. In the ninth C site, C(9) is bonded in a distorted bent 120 degrees geometry to one C(10), one O(7), and one O(8) atom. The C(9)-C(10) bond length is 1.54 Å. The C(9)-O(7) bond length is 1.31 Å. The C(9)-O(8) bond length is 1.24 Å. In the tenth C site, C(10) is bonded in a trigonal planar geometry to one C(11), one C(12), and one C(9) atom. The C(10)-C(11) bond length is 1.51 Å. The C(10)-C(12) bond length is 1.31 Å. In the eleventh C site, C(11) is bonded in a distorted single-bond geometry to one C(10); one C(24); and one H(3,6) atom. The C(11)-C(24) bond length is 1.43 Å. The C(11)-H(3,6) bond length is 1.14 Å. In the twelfth C site, C(12) is bonded in a single-bond geometry to one C(10), one C(23), and one O(9) atom. The C(12)-C(23) bond length is 1.43 Å. The C(12)-O(9) bond length is 1.39 Å. In the thirteenth C site, C(13,17) is bonded in a distorted bent 120 degrees geometry to one C(14); one O(10,13); and one O(11) atom. The C(13,17)-C(14) bond length is 1.54 Å. The C(13,17)-O(10,13) bond length is 1.31 Å. The C(13,17)-O(11) bond length is 1.24 Å. In the fourteenth C site, C(14) is bonded in a trigonal planar geometry to one C(13,17); one C(15,19); and one C(16) atom. The C(14)-C(15,19) bond length is 1.51 Å. The C(14)-C(16) bond length is 1.31 Å. In the fifteenth C site, C(15,19) is bonded in a distorted single-bond geometry to one C(14); one C(4); and one H(4,5) atom. The C(15,19)-H(4,5) bond length is 1.14 Å. In the sixteenth C site, C(16) is bonded in a single-bond geometry to one C(14) and one O(12) atom. The C(16)-O(12) bond length is 1.39 Å. In the seventeenth C site, C(18) is bonded in a trigonal planar geometry to one C(13,17); one C(15,19); and one C(20) atom. The C(18)-C(13,17) bond length is 1.54 Å. The C(18)-C(15,19) bond length is 1.51 Å. The C(18)-C(20) bond length is 1.31 Å. In the eighteenth C site, C(20) is bonded in a single-bond geometry to one C(18), one C(7), and one O(15) atom. The C(20)-O(15) bond length is 1.39 Å. In the nineteenth C site, C(21) is bonded in a distorted bent 120 degrees geometry to one C(22), one O(16), and one O(17) atom. The C(21)-C(22) bond length is 1.54 Å. The C(21)-O(16) bond length is 1.31 Å. The C(21)-O(17) bond length is 1.24 Å. In the twentieth C site, C(22) is bonded in a trigonal planar geometry to one C(21), one C(23), and one C(24) atom. The C(22)-C(23) bond length is 1.51 Å. The C(22)-C(24) bond length is 1.31 Å. In the twenty-first C site, C(23) is bonded in a distorted single-bond geometry to one C(12); one C(22); and one H(3,6) atom. The C(23)-H(3,6) bond length is 1.14 Å. In the twenty-second C site, C(24) is bonded in a single-bond geometry to one C(11), one C(22), and one O(18) atom. The C(24)-O(18) bond length is 1.39 Å. There are four 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(7) atom. In the third H site, H(3,6) is bonded in a single-bond geometry to one C(11) atom. In the fourth H site, H(4,5) is bonded in a single-bond geometry to one C(15,19) atom. There are seventeen 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 T-shaped geometry to one Mg(2), one Mg(3), and one C(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Mg(1), one Mg(3), and one C(4) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Mg(2) and one C(5) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(3), and one C(5) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Mg(1), one Mg(2), and one C(8) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one Mg(3) and one C(9) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(2), and one C(9) atom. In the ninth O site, O(9) is bonded in a trigonal planar geometry to one Mg(2), one Mg(3), and one C(12) atom. In the tenth O site, O(10,13) is bonded in a bent 120 degrees geometry to one Mg(4) and one C(13,17) atom. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one Mg(5); one Mg(6); and one C(13,17) atom. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Mg(4), one Mg(6), and one C(16) atom. In the thirteenth O site, O(14) is bonded in a distorted T-shaped geometry to one Mg(4); one Mg(6); and one C(13,17) atom. The O(14)-C(13,17) bond length is 1.24 Å. In the fourteenth O site, O(15) is bonded in a trigonal planar geometry to one Mg(4), one Mg(5), and one C(20) atom. In the fifteenth O site, O(16) is bonded in a bent 120 degrees geometry to one Mg(6) and one C(21) atom. In the sixteenth O site, O(17) is bonded in a distorted T-shaped geometry to one Mg(4), one Mg(5), and one C(21) atom. In the seventeenth O site, O(18) is bonded in a trigonal planar geometry to one Mg(5), one Mg(6), and one C(24) atom. Linkers: 2 [O]C(=O)c1cc([O])c([C]=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 11.64 A, density 0.91 g/cm3, surface area 3348.29 m2/g, accessible volume 0.61 cm3/g