Mg(PO5)2 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with four equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-28°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one P(1) and one O(4) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one P(1) and one O(4) atom. In the third O site, O(3) is bonded in a linear geometry to one Mg(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Mg(1), one O(1), and one O(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(1) atom.
Mg(PO5)2 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with four equivalent P(1)O4 tetrahedra. Both Mg(1)-O(3) bond lengths are 2.01 Å. Both Mg(1)-O(4) bond lengths are 2.63 Å. Both Mg(1)-O(5) bond lengths are 2.01 Å. P(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-28°. The P(1)-O(1) bond length is 1.62 Å. The P(1)-O(2) bond length is 1.70 Å. The P(1)-O(3) bond length is 1.49 Å. The P(1)-O(5) bond length is 1.49 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one P(1) and one O(4) atom. The O(1)-O(4) bond length is 1.58 Å. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one P(1) and one O(4) atom. The O(2)-O(4) bond length is 1.39 Å. In the third O site, O(3) is bonded in a linear geometry to one Mg(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Mg(1), one O(1), and one O(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(1) atom.