MgPH2(CO4)2 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to one O(1), one O(3), one O(5), one O(6), one O(7), and one O(8) atom to form MgO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra. The Mg(1)-O(1) bond length is 2.04 Å. The Mg(1)-O(3) bond length is 2.01 Å. The Mg(1)-O(5) bond length is 2.17 Å. The Mg(1)-O(6) bond length is 2.14 Å. The Mg(1)-O(7) bond length is 2.11 Å. The Mg(1)-O(8) bond length is 2.13 Å. There are two inequivalent C sites. In the first C site, 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. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one O(7) and one O(8) atom. The C(2)-O(7) bond length is 1.25 Å. The C(2)-O(8) 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 two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-43°. The P(1)-O(1) bond length is 1.50 Å. The P(1)-O(2) bond length is 1.57 Å. The P(1)-O(3) bond length is 1.49 Å. The P(1)-O(4) bond length is 1.58 Å. 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 0.82 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(4) atom. The H(2)-O(4) bond length is 0.82 Å. There are eight 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 water-like geometry to one P(1) and one H(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(2) 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. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one Mg(1) and one C(2) atom. In the eighth O site, O(8) is bonded in a bent 120 degrees geometry to one Mg(1) and one C(2) atom. Linkers: 2 [O]C(=O)C([O])=O. Metal clusters: 4 [Mg]. The MOF has largest included sphere 4.49 A, density 1.31 g/cm3, surface area 3970.12 m2/g, accessible volume 0.33 cm3/g