MgCPHO6 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form MgO5 square pyramids that share corners with three equivalent P(1)O4 tetrahedra. The Mg(1)-O(1) bond length is 2.04 Å. The Mg(1)-O(2) bond length is 2.04 Å. The Mg(1)-O(3) bond length is 2.03 Å. The Mg(1)-O(5) bond length is 2.14 Å. The Mg(1)-O(6) bond length is 2.17 Å. C(1) is bonded in a distorted bent 120 degrees geometry to one O(5) and one O(6) atom. The C(1)-O(5) bond length is 1.25 Å. The C(1)-O(6) bond length is 1.25 Å. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Mg(1)O5 square pyramids. The P(1)-O(1) bond length is 1.52 Å. The P(1)-O(2) bond length is 1.52 Å. The P(1)-O(3) bond length is 1.52 Å. The P(1)-O(4) bond length is 1.59 Å. H(1) is bonded in a single-bond geometry to one O(4) atom. The H(1)-O(4) bond length is 0.82 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a water-like geometry to one P(1) and one H(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Mg(1) and one C(1) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Mg(1) and one C(1) atom. Linkers: 1 [O]C(=O)C([O])=O. Metal clusters: 4 [Mg]. The MOF has largest included sphere 4.17 A, density 1.47 g/cm3, surface area 3533.65 m2/g, accessible volume 0.37 cm3/g