K3NaMgCr2O8 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a linear geometry to two equivalent O(2) atoms. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(1), and three equivalent O(2) atoms. Na(1) is bonded in a square co-planar geometry to four equivalent O(1) atoms. Mg(1) is bonded in a square co-planar geometry to four equivalent O(1) atoms. Cr(1) is bonded in a tetrahedral geometry to one O(2), one O(3), and two equivalent O(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one K(2), one Na(1), one Mg(1), and one Cr(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), three equivalent K(2), and one Cr(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one K(2) and one Cr(1) atom.
K3NaMgCr2O8 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a linear geometry to two equivalent O(2) atoms. Both K(1)-O(2) bond lengths are 2.90 Å. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(1), and three equivalent O(2) atoms. The K(2)-O(3) bond length is 2.59 Å. Both K(2)-O(1) bond lengths are 2.69 Å. There is one shorter (2.93 Å) and two longer (3.12 Å) K(2)-O(2) bond lengths. Na(1) is bonded in a square co-planar geometry to four equivalent O(1) atoms. All Na(1)-O(1) bond lengths are 2.31 Å. Mg(1) is bonded in a square co-planar geometry to four equivalent O(1) atoms. All Mg(1)-O(1) bond lengths are 2.00 Å. Cr(1) is bonded in a tetrahedral geometry to one O(2), one O(3), and two equivalent O(1) atoms. The Cr(1)-O(2) bond length is 1.69 Å. The Cr(1)-O(3) bond length is 1.66 Å. Both Cr(1)-O(1) bond lengths are 1.81 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one K(2), one Na(1), one Mg(1), and one Cr(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), three equivalent K(2), and one Cr(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one K(2) and one Cr(1) atom.