MgCr2(PO5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one O(6), and one O(8) atom. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(10), one O(2), one O(3), one O(4), and one O(6) atom to form distorted CrO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. In the second Cr site, Cr(2) is bonded to one O(1), one O(5), one O(7), one O(8), and one O(9) atom to form CrO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O5 trigonal bipyramids and corners with two equivalent Cr(2)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(10), one O(6), one O(7), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O5 trigonal bipyramids and corners with two equivalent Cr(2)O5 trigonal bipyramids. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 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 an L-shaped geometry to one Mg(1) and one Cr(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(2), and one P(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Cr(2) and one P(2) atom. In the eighth O site, O(8) is bonded in a water-like geometry to one Mg(1) and one Cr(2) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Cr(2) and one P(2) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(2) atom.
MgCr2(PO5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one O(6), and one O(8) atom. The Mg(1)-O(2) bond length is 2.28 Å. The Mg(1)-O(3) bond length is 2.09 Å. The Mg(1)-O(5) bond length is 2.01 Å. The Mg(1)-O(6) bond length is 2.04 Å. The Mg(1)-O(8) bond length is 2.02 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(3), one O(4), and one O(6) atom to form distorted CrO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. The Cr(1)-O(10) bond length is 1.90 Å. The Cr(1)-O(2) bond length is 1.93 Å. The Cr(1)-O(3) bond length is 1.68 Å. The Cr(1)-O(4) bond length is 1.89 Å. The Cr(1)-O(6) bond length is 2.14 Å. In the second Cr site, Cr(2) is bonded to one O(1), one O(5), one O(7), one O(8), and one O(9) atom to form CrO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. The Cr(2)-O(1) bond length is 1.94 Å. The Cr(2)-O(5) bond length is 2.11 Å. The Cr(2)-O(7) bond length is 1.90 Å. The Cr(2)-O(8) bond length is 1.69 Å. The Cr(2)-O(9) bond length is 1.88 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(4), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O5 trigonal bipyramids and corners with two equivalent Cr(2)O5 trigonal bipyramids. The P(1)-O(1) bond length is 1.52 Å. The P(1)-O(2) bond length is 1.56 Å. The P(1)-O(4) bond length is 1.55 Å. The P(1)-O(5) bond length is 1.56 Å. In the second P site, P(2) is bonded to one O(10), one O(6), one O(7), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O5 trigonal bipyramids and corners with two equivalent Cr(2)O5 trigonal bipyramids. The P(2)-O(10) bond length is 1.54 Å. The P(2)-O(6) bond length is 1.55 Å. The P(2)-O(7) bond length is 1.55 Å. The P(2)-O(9) bond length is 1.55 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 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 an L-shaped geometry to one Mg(1) and one Cr(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(2), and one P(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Cr(2) and one P(2) atom. In the eighth O site, O(8) is bonded in a water-like geometry to one Mg(1) and one Cr(2) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Cr(2) and one P(2) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(2) atom.