MgCrP2O7 crystallizes in the triclinic P1 space group. 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 MgO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. Cr(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(7) atom. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), 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 32-54°. In the second P site, P(2) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-54°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Cr(1), and one P(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees 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 trigonal planar geometry to one Mg(1), one Cr(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Mg(1), one Cr(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(1), one Cr(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Mg(1), one Cr(1), and one P(1) atom.
MgCrP2O7 crystallizes in the triclinic P1 space group. 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 MgO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. The Mg(1)-O(1) bond length is 2.25 Å. The Mg(1)-O(2) bond length is 2.02 Å. The Mg(1)-O(3) bond length is 2.08 Å. The Mg(1)-O(4) bond length is 2.01 Å. The Mg(1)-O(6) bond length is 2.08 Å. The Mg(1)-O(7) bond length is 2.24 Å. Cr(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(7) atom. The Cr(1)-O(1) bond length is 2.11 Å. The Cr(1)-O(2) bond length is 2.60 Å. The Cr(1)-O(3) bond length is 2.12 Å. The Cr(1)-O(4) bond length is 2.71 Å. The Cr(1)-O(6) bond length is 2.11 Å. The Cr(1)-O(7) bond length is 2.12 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(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 32-54°. The P(1)-O(2) bond length is 1.51 Å. The P(1)-O(3) bond length is 1.54 Å. The P(1)-O(5) bond length is 1.61 Å. The P(1)-O(7) bond length is 1.55 Å. In the second P site, P(2) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-54°. The P(2)-O(1) bond length is 1.54 Å. The P(2)-O(4) bond length is 1.51 Å. The P(2)-O(5) bond length is 1.61 Å. The P(2)-O(6) bond length is 1.54 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Cr(1), and one P(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees 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 trigonal planar geometry to one Mg(1), one Cr(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Mg(1), one Cr(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(1), one Cr(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Mg(1), one Cr(1), and one P(1) atom.