NaMgCr3O8 crystallizes in the monoclinic C2 space group. Na(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(4) atoms. 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 to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-56°. In the second Cr site, Cr(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing CrO6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Cr(1), and one Cr(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one Cr(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Cr(1) and one Cr(2) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(1), one Mg(1), and one Cr(1) atom.
NaMgCr3O8 crystallizes in the monoclinic C2 space group. Na(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(4) atoms. Both Na(1)-O(1) bond lengths are 2.24 Å. There are two shorter (2.49 Å) and two longer (2.85 Å) Na(1)-O(4) bond lengths. 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 2.04 Å. Both Mg(1)-O(4) bond lengths are 2.07 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-56°. The Cr(1)-O(1) bond length is 1.72 Å. The Cr(1)-O(2) bond length is 1.83 Å. The Cr(1)-O(3) bond length is 1.67 Å. The Cr(1)-O(4) bond length is 1.75 Å. In the second Cr site, Cr(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing CrO6 octahedra. Both Cr(2)-O(1) bond lengths are 2.01 Å. Both Cr(2)-O(2) bond lengths are 2.08 Å. Both Cr(2)-O(3) bond lengths are 1.95 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Cr(1), and one Cr(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one Cr(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Cr(1) and one Cr(2) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(1), one Mg(1), and one Cr(1) atom.