MgV4(PO5)4 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(10), two equivalent O(3), and two equivalent O(9) atoms to form distorted MgO6 octahedra that share corners with two equivalent V(2)O6 octahedra, corners with four equivalent P(2)O4 tetrahedra, and faces with two equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are three inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(8), and one O(9) atom to form distorted VO6 octahedra that share  a cornercorner with one V(2)O6 octahedra,  a cornercorner with one V(3)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-38°. In the second V site, V(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form VO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent V(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-51°. In the third V site, V(3) is bonded to two equivalent O(6), two equivalent O(7), and two equivalent O(8) atoms to form VO6 octahedra that share corners with two equivalent V(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 30°. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one V(2)O6 octahedra,  a cornercorner with one V(3)O6 octahedra, and corners with two equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-41°. In the second P site, P(2) is bonded to one O(10), one O(4), one O(6), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one V(2)O6 octahedra,  a cornercorner with one V(3)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, and corners with two equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-50°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one V(1) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one V(1) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one V(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one V(2) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one V(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one V(3) and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one V(3) and one P(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one V(1) and one V(3) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one P(2) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one P(2) atom.
MgV4(PO5)4 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(10), two equivalent O(3), and two equivalent O(9) atoms to form distorted MgO6 octahedra that share corners with two equivalent V(2)O6 octahedra, corners with four equivalent P(2)O4 tetrahedra, and faces with two equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. Both Mg(1)-O(10) bond lengths are 2.07 Å. Both Mg(1)-O(3) bond lengths are 2.22 Å. Both Mg(1)-O(9) bond lengths are 2.03 Å. There are three inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(8), and one O(9) atom to form distorted VO6 octahedra that share  a cornercorner with one V(2)O6 octahedra,  a cornercorner with one V(3)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-38°. The V(1)-O(1) bond length is 1.88 Å. The V(1)-O(10) bond length is 2.16 Å. The V(1)-O(2) bond length is 1.92 Å. The V(1)-O(3) bond length is 1.98 Å. The V(1)-O(8) bond length is 1.78 Å. The V(1)-O(9) bond length is 2.09 Å. In the second V site, V(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form VO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent V(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-51°. Both V(2)-O(3) bond lengths are 1.85 Å. Both V(2)-O(4) bond lengths are 1.97 Å. Both V(2)-O(5) bond lengths are 1.92 Å. In the third V site, V(3) is bonded to two equivalent O(6), two equivalent O(7), and two equivalent O(8) atoms to form VO6 octahedra that share corners with two equivalent V(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 30°. Both V(3)-O(6) bond lengths are 1.92 Å. Both V(3)-O(7) bond lengths are 1.90 Å. Both V(3)-O(8) bond lengths are 1.84 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one V(2)O6 octahedra,  a cornercorner with one V(3)O6 octahedra, and corners with two equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-41°. The P(1)-O(1) bond length is 1.53 Å. The P(1)-O(2) bond length is 1.53 Å. The P(1)-O(5) bond length is 1.55 Å. The P(1)-O(7) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(10), one O(4), one O(6), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one V(2)O6 octahedra,  a cornercorner with one V(3)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, and corners with two equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-50°. The P(2)-O(10) bond length is 1.55 Å. The P(2)-O(4) bond length is 1.54 Å. The P(2)-O(6) bond length is 1.55 Å. The P(2)-O(9) bond length is 1.56 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one V(1) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one V(1) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one V(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one V(2) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one V(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one V(3) and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one V(3) and one P(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one V(1) and one V(3) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one P(2) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Mg(1), one V(1), and one P(2) atom.