BaMgP2O7 crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded in a 10-coordinate geometry to one O(2), one O(3), two equivalent O(1), two equivalent O(4), two equivalent O(6), and two equivalent O(7) atoms. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form distorted MgO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-47°. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 20°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(6) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Mg(1), and one P(2) atom. In the third O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Mg(1), and one P(1) atom. In the fourth O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Ba(1), one Mg(1), and one P(2) atom. In the fifth O site, O(2) is bonded in a 3-coordinate geometry to one Ba(1), one Mg(1), and one P(1) atom. In the sixth O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), one Mg(1), and one P(2) atom. In the seventh O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Mg(1), and one P(1) atom.
BaMgP2O7 crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded in a 10-coordinate geometry to one O(2), one O(3), two equivalent O(1), two equivalent O(4), two equivalent O(6), and two equivalent O(7) atoms. The Ba(1)-O(2) bond length is 2.87 Å. The Ba(1)-O(3) bond length is 2.90 Å. There is one shorter (2.73 Å) and one longer (2.78 Å) Ba(1)-O(1) bond length. There is one shorter (3.00 Å) and one longer (3.38 Å) Ba(1)-O(4) bond length. There is one shorter (2.76 Å) and one longer (2.85 Å) Ba(1)-O(6) bond length. There is one shorter (2.91 Å) and one longer (3.25 Å) Ba(1)-O(7) bond length. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form distorted MgO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. The Mg(1)-O(1) bond length is 2.53 Å. The Mg(1)-O(2) bond length is 2.03 Å. The Mg(1)-O(3) bond length is 2.01 Å. The Mg(1)-O(4) bond length is 2.08 Å. The Mg(1)-O(6) bond length is 2.17 Å. The Mg(1)-O(7) bond length is 2.10 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-47°. The P(1)-O(2) bond length is 1.53 Å. The P(1)-O(4) bond length is 1.53 Å. The P(1)-O(5) bond length is 1.64 Å. The P(1)-O(7) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 20°. The P(2)-O(1) bond length is 1.53 Å. The P(2)-O(3) bond length is 1.52 Å. The P(2)-O(5) bond length is 1.62 Å. The P(2)-O(6) bond length is 1.55 Å. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(6) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Mg(1), and one P(2) atom. In the third O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Mg(1), and one P(1) atom. In the fourth O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Ba(1), one Mg(1), and one P(2) atom. In the fifth O site, O(2) is bonded in a 3-coordinate geometry to one Ba(1), one Mg(1), and one P(1) atom. In the sixth O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), one Mg(1), and one P(2) atom. In the seventh O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Mg(1), and one P(1) atom.