MgV3(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(7) atoms to form VO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one V(1)O6 octahedra, and  an edgeedge with one V(2)O6 octahedra. In the second V site, V(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form VO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra, and edges with two equivalent V(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one V(2)O6 octahedra, corners with three equivalent V(1)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-64°. In the second P site, P(2) is bonded to one O(1), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent V(2)O6 octahedra, corners with three equivalent V(1)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-63°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one P(1) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one V(1), one V(2), and one P(2) atom. In the third O site, O(7) is bonded in a distorted trigonal planar geometry to two equivalent V(1) and one P(2) atom. In the fourth O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one V(2), and one P(2) atom. In the fifth O site, O(2) is bonded in a 4-coordinate geometry to one Mg(1), one V(1), one V(2), and one P(1) atom. In the sixth O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one P(1) atom. In the seventh O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom.
MgV3(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. Both Mg(1)-O(1) bond lengths are 2.27 Å. Both Mg(1)-O(2) bond lengths are 2.51 Å. Both Mg(1)-O(3) bond lengths are 2.50 Å. Both Mg(1)-O(5) bond lengths are 2.65 Å. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(7) atoms to form VO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one V(1)O6 octahedra, and  an edgeedge with one V(2)O6 octahedra. The V(1)-O(2) bond length is 2.19 Å. The V(1)-O(3) bond length is 2.24 Å. The V(1)-O(5) bond length is 2.18 Å. The V(1)-O(6) bond length is 2.14 Å. Both V(1)-O(7) bond lengths are 2.15 Å. In the second V site, V(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form VO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra, and edges with two equivalent V(1)O6 octahedra. Both V(2)-O(1) bond lengths are 2.25 Å. Both V(2)-O(2) bond lengths are 2.19 Å. Both V(2)-O(6) bond lengths are 2.17 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one V(2)O6 octahedra, corners with three equivalent V(1)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-64°. The P(1)-O(2) bond length is 1.56 Å. The P(1)-O(3) bond length is 1.53 Å. The P(1)-O(4) bond length is 1.61 Å. The P(1)-O(5) bond length is 1.52 Å. In the second P site, P(2) is bonded to one O(1), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent V(2)O6 octahedra, corners with three equivalent V(1)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-63°. The P(2)-O(1) bond length is 1.54 Å. The P(2)-O(4) bond length is 1.60 Å. The P(2)-O(6) bond length is 1.53 Å. The P(2)-O(7) bond length is 1.53 Å. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one P(1) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one V(1), one V(2), and one P(2) atom. In the third O site, O(7) is bonded in a distorted trigonal planar geometry to two equivalent V(1) and one P(2) atom. In the fourth O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one V(2), and one P(2) atom. In the fifth O site, O(2) is bonded in a 4-coordinate geometry to one Mg(1), one V(1), one V(2), and one P(1) atom. In the sixth O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one P(1) atom. In the seventh O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom.