MgCr3O7 crystallizes in the orthorhombic Pnma space group. Mg(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of distorted edge and corner-sharing CrO5 trigonal bipyramids. In the second Cr site, Cr(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of distorted edge and corner-sharing CrO5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(3) is bonded in a bent 120 degrees geometry to one Mg(1) and one Cr(2) atom. In the second O site, O(4) is bonded in a bent 150 degrees geometry to one Mg(1) and one Cr(1) atom. In the third O site, O(1) is bonded to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms to form a mixture of distorted edge and corner-sharing OMgCr3 trigonal pyramids. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms.
MgCr3O7 crystallizes in the orthorhombic Pnma space group. Mg(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. The Mg(1)-O(3) bond length is 2.07 Å. Both Mg(1)-O(1) bond lengths are 2.19 Å. Both Mg(1)-O(2) bond lengths are 2.56 Å. Both Mg(1)-O(4) bond lengths are 2.02 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of distorted edge and corner-sharing CrO5 trigonal bipyramids. The Cr(1)-O(4) bond length is 1.65 Å. There is one shorter (1.92 Å) and one longer (1.93 Å) Cr(1)-O(1) bond length. There is one shorter (1.91 Å) and one longer (1.93 Å) Cr(1)-O(2) bond length. In the second Cr site, Cr(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of distorted edge and corner-sharing CrO5 trigonal bipyramids. The Cr(2)-O(3) bond length is 1.67 Å. Both Cr(2)-O(1) bond lengths are 1.95 Å. Both Cr(2)-O(2) bond lengths are 1.90 Å. There are four inequivalent O sites. In the first O site, O(3) is bonded in a bent 120 degrees geometry to one Mg(1) and one Cr(2) atom. In the second O site, O(4) is bonded in a bent 150 degrees geometry to one Mg(1) and one Cr(1) atom. In the third O site, O(1) is bonded to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms to form a mixture of distorted edge and corner-sharing OMgCr3 trigonal pyramids. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms.