MgCr2(NiO4)2 crystallizes in the orthorhombic Amm2 space group. Mg(1) is bonded in a 4-coordinate geometry to 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 in a tetrahedral geometry to two equivalent O(2) and two equivalent O(4) atoms. In the second Cr site, Cr(2) is bonded in a tetrahedral geometry to two equivalent O(1) and two equivalent O(3) atoms. Ni(1) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Cr(2) and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded to one Mg(1), one Cr(1), and two equivalent Ni(1) atoms to form a mixture of distorted face and corner-sharing OMgCrNi2 tetrahedra. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Cr(2) and one Ni(1) atom. In the fourth O site, O(4) is bonded in an L-shaped geometry to one Mg(1) and one Cr(1) atom.
MgCr2(NiO4)2 crystallizes in the orthorhombic Amm2 space group. Mg(1) is bonded in a 4-coordinate geometry to two equivalent O(2) and two equivalent O(4) atoms. Both Mg(1)-O(2) bond lengths are 1.96 Å. Both Mg(1)-O(4) bond lengths are 1.97 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a tetrahedral geometry to two equivalent O(2) and two equivalent O(4) atoms. Both Cr(1)-O(2) bond lengths are 1.77 Å. Both Cr(1)-O(4) bond lengths are 1.69 Å. In the second Cr site, Cr(2) is bonded in a tetrahedral geometry to two equivalent O(1) and two equivalent O(3) atoms. Both Cr(2)-O(1) bond lengths are 1.79 Å. Both Cr(2)-O(3) bond lengths are 1.71 Å. Ni(1) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. The Ni(1)-O(3) bond length is 2.00 Å. Both Ni(1)-O(1) bond lengths are 2.06 Å. Both Ni(1)-O(2) bond lengths are 2.20 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Cr(2) and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded to one Mg(1), one Cr(1), and two equivalent Ni(1) atoms to form a mixture of distorted face and corner-sharing OMgCrNi2 tetrahedra. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Cr(2) and one Ni(1) atom. In the fourth O site, O(4) is bonded in an L-shaped geometry to one Mg(1) and one Cr(1) atom.