K6MgCr2O8 crystallizes in the orthorhombic P222 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form KO4 tetrahedra that share corners with two equivalent Cr(1)O4 tetrahedra, corners with two equivalent Cr(2)O4 tetrahedra, and corners with four equivalent K(2)O4 tetrahedra. In the second K site, K(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted KO4 tetrahedra that share corners with two equivalent Cr(1)O4 tetrahedra, corners with two equivalent Cr(2)O4 tetrahedra, and corners with four equivalent K(1)O4 tetrahedra. In the third K site, K(3) is bonded in a distorted rectangular see-saw-like geometry to four equivalent O(1) atoms. In the fourth K site, K(4) is bonded in a 4-coordinate geometry to four equivalent O(2) atoms. Mg(1) is bonded in a 4-coordinate geometry to four equivalent O(2) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to four equivalent O(2) atoms to form distorted CrO4 tetrahedra that share corners with four equivalent K(1)O4 tetrahedra and corners with four equivalent K(2)O4 tetrahedra. In the second Cr site, Cr(2) is bonded to four equivalent O(1) atoms to form CrO4 tetrahedra that share corners with four equivalent K(1)O4 tetrahedra and corners with four equivalent K(2)O4 tetrahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one K(1), one K(2), one K(3), and one Cr(2) atom. In the second O site, O(2) is bonded to one K(1), one K(2), one K(4), one Mg(1), and one Cr(1) atom to form a mixture of distorted corner and edge-sharing OK3MgCr trigonal bipyramids.
K6MgCr2O8 crystallizes in the orthorhombic P222 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form KO4 tetrahedra that share corners with two equivalent Cr(1)O4 tetrahedra, corners with two equivalent Cr(2)O4 tetrahedra, and corners with four equivalent K(2)O4 tetrahedra. Both K(1)-O(1) bond lengths are 2.73 Å. Both K(1)-O(2) bond lengths are 2.87 Å. In the second K site, K(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted KO4 tetrahedra that share corners with two equivalent Cr(1)O4 tetrahedra, corners with two equivalent Cr(2)O4 tetrahedra, and corners with four equivalent K(1)O4 tetrahedra. Both K(2)-O(1) bond lengths are 2.58 Å. Both K(2)-O(2) bond lengths are 2.69 Å. In the third K site, K(3) is bonded in a distorted rectangular see-saw-like geometry to four equivalent O(1) atoms. All K(3)-O(1) bond lengths are 2.79 Å. In the fourth K site, K(4) is bonded in a 4-coordinate geometry to four equivalent O(2) atoms. All K(4)-O(2) bond lengths are 2.65 Å. Mg(1) is bonded in a 4-coordinate geometry to four equivalent O(2) atoms. All Mg(1)-O(2) bond lengths are 1.98 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to four equivalent O(2) atoms to form distorted CrO4 tetrahedra that share corners with four equivalent K(1)O4 tetrahedra and corners with four equivalent K(2)O4 tetrahedra. All Cr(1)-O(2) bond lengths are 1.94 Å. In the second Cr site, Cr(2) is bonded to four equivalent O(1) atoms to form CrO4 tetrahedra that share corners with four equivalent K(1)O4 tetrahedra and corners with four equivalent K(2)O4 tetrahedra. All Cr(2)-O(1) bond lengths are 1.74 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one K(1), one K(2), one K(3), and one Cr(2) atom. In the second O site, O(2) is bonded to one K(1), one K(2), one K(4), one Mg(1), and one Cr(1) atom to form a mixture of distorted corner and edge-sharing OK3MgCr trigonal bipyramids.