MgCr2(PO5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(10), one O(2), one O(4), one O(5), one O(7), and one O(9) atom to form distorted MgO6 octahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and faces with two equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(10), one O(2), one O(4), one O(5), one O(7), and one O(9) atom to form CrO6 octahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 42°. In the second Cr site, Cr(2) is bonded to one O(1), one O(10), one O(3), one O(6), one O(8), and one O(9) atom to form CrO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Cr(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 42-48°. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Cr(1)O6 octahedra, and corners with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-50°. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Cr(1)O6 octahedra, and corners with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-49°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Cr(2) and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Cr(2) and one P(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Cr(2) and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Cr(2) and one P(1) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one Cr(2) atom. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one Cr(2) atom.
MgCr2(PO5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(10), one O(2), one O(4), one O(5), one O(7), and one O(9) atom to form distorted MgO6 octahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and faces with two equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. The Mg(1)-O(10) bond length is 2.08 Å. The Mg(1)-O(2) bond length is 2.04 Å. The Mg(1)-O(4) bond length is 2.04 Å. The Mg(1)-O(5) bond length is 2.12 Å. The Mg(1)-O(7) bond length is 2.12 Å. The Mg(1)-O(9) bond length is 2.09 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(10), one O(2), one O(4), one O(5), one O(7), and one O(9) atom to form CrO6 octahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 42°. The Cr(1)-O(10) bond length is 1.88 Å. The Cr(1)-O(2) bond length is 2.00 Å. The Cr(1)-O(4) bond length is 2.00 Å. The Cr(1)-O(5) bond length is 2.00 Å. The Cr(1)-O(7) bond length is 2.01 Å. The Cr(1)-O(9) bond length is 1.85 Å. In the second Cr site, Cr(2) is bonded to one O(1), one O(10), one O(3), one O(6), one O(8), and one O(9) atom to form CrO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Cr(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 42-48°. The Cr(2)-O(1) bond length is 1.92 Å. The Cr(2)-O(10) bond length is 1.89 Å. The Cr(2)-O(3) bond length is 1.92 Å. The Cr(2)-O(6) bond length is 2.00 Å. The Cr(2)-O(8) bond length is 2.00 Å. The Cr(2)-O(9) bond length is 1.94 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(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Cr(1)O6 octahedra, and corners with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-50°. The P(1)-O(1) bond length is 1.55 Å. The P(1)-O(2) bond length is 1.57 Å. The P(1)-O(7) bond length is 1.56 Å. The P(1)-O(8) bond length is 1.52 Å. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Cr(1)O6 octahedra, and corners with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-49°. The P(2)-O(3) bond length is 1.55 Å. The P(2)-O(4) bond length is 1.57 Å. The P(2)-O(5) bond length is 1.56 Å. The P(2)-O(6) bond length is 1.52 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Cr(2) and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Cr(2) and one P(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Cr(2) and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Cr(2) and one P(1) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one Cr(2) atom. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one Cr(2) atom.