K6Mg(SbO4)2 crystallizes in the triclinic P1 space group. There are six inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(5), one O(6), and one O(7) atom. In the second K site, K(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form distorted KO4 tetrahedra that share corners with two equivalent Sb(1)O6 octahedra,  a cornercorner with one K(4)O5 trigonal bipyramid, and  an edgeedge with one K(4)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 15-56°. In the third K site, K(3) is bonded in a 4-coordinate geometry to one O(3), one O(5), one O(6), one O(7), and one O(8) atom. In the fourth K site, K(4) is bonded to one O(1), one O(2), one O(4), one O(5), and one O(6) atom to form distorted KO5 trigonal bipyramids that share  a cornercorner with one Sb(1)O6 octahedra,  a cornercorner with one K(2)O4 tetrahedra,  an edgeedge with one Sb(1)O6 octahedra, and  an edgeedge with one K(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 28°. In the fifth K site, K(5) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), one O(6), and one O(8) atom. In the sixth K site, K(6) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), one O(7), and one O(8) atom. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(4), one O(7), and one O(8) atom. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form SbO6 octahedra that share corners with two equivalent K(2)O4 tetrahedra,  a cornercorner with one K(4)O5 trigonal bipyramid, and  an edgeedge with one K(4)O5 trigonal bipyramid. In the second Sb site, Sb(2) is bonded in a distorted trigonal non-coplanar geometry to one O(2), one O(5), and one O(6) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one K(4), one K(5), one K(6), one Mg(1), and one Sb(1) atom. In the second O site, O(2) is bonded to one K(4), one K(5), one K(6), one Sb(1), and one Sb(2) atom to form distorted edge-sharing OK3Sb2 trigonal bipyramids. In the third O site, O(3) is bonded to one K(1), one K(2), one K(3), one K(5), and one Sb(1) atom to form distorted edge-sharing OK4Sb trigonal bipyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one K(1), one K(2), one K(4), one Mg(1), and one Sb(1) atom. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one K(1), one K(2), one K(3), one K(4), one K(6), and one Sb(2) atom. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one K(1), one K(2), one K(3), one K(4), one K(5), and one Sb(2) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one K(1), one K(3), one K(6), one Mg(1), and one Sb(1) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one K(3), one K(5), one K(6), one Mg(1), and one Sb(1) atom.
K6Mg(SbO4)2 crystallizes in the triclinic P1 space group. There are six inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(5), one O(6), and one O(7) atom. The K(1)-O(3) bond length is 2.64 Å. The K(1)-O(4) bond length is 2.69 Å. The K(1)-O(5) bond length is 3.26 Å. The K(1)-O(6) bond length is 2.72 Å. The K(1)-O(7) bond length is 2.70 Å. In the second K site, K(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form distorted KO4 tetrahedra that share corners with two equivalent Sb(1)O6 octahedra,  a cornercorner with one K(4)O5 trigonal bipyramid, and  an edgeedge with one K(4)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 15-56°. The K(2)-O(3) bond length is 2.63 Å. The K(2)-O(4) bond length is 2.70 Å. The K(2)-O(5) bond length is 2.66 Å. The K(2)-O(6) bond length is 2.67 Å. In the third K site, K(3) is bonded in a 4-coordinate geometry to one O(3), one O(5), one O(6), one O(7), and one O(8) atom. The K(3)-O(3) bond length is 2.68 Å. The K(3)-O(5) bond length is 2.88 Å. The K(3)-O(6) bond length is 3.22 Å. The K(3)-O(7) bond length is 2.93 Å. The K(3)-O(8) bond length is 2.62 Å. In the fourth K site, K(4) is bonded to one O(1), one O(2), one O(4), one O(5), and one O(6) atom to form distorted KO5 trigonal bipyramids that share  a cornercorner with one Sb(1)O6 octahedra,  a cornercorner with one K(2)O4 tetrahedra,  an edgeedge with one Sb(1)O6 octahedra, and  an edgeedge with one K(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 28°. The K(4)-O(1) bond length is 2.95 Å. The K(4)-O(2) bond length is 2.93 Å. The K(4)-O(4) bond length is 2.86 Å. The K(4)-O(5) bond length is 2.65 Å. The K(4)-O(6) bond length is 2.89 Å. In the fifth K site, K(5) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), one O(6), and one O(8) atom. The K(5)-O(1) bond length is 2.52 Å. The K(5)-O(2) bond length is 2.75 Å. The K(5)-O(3) bond length is 2.62 Å. The K(5)-O(6) bond length is 3.31 Å. The K(5)-O(8) bond length is 2.59 Å. In the sixth K site, K(6) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), one O(7), and one O(8) atom. The K(6)-O(1) bond length is 2.72 Å. The K(6)-O(2) bond length is 2.64 Å. The K(6)-O(5) bond length is 2.76 Å. The K(6)-O(7) bond length is 2.97 Å. The K(6)-O(8) bond length is 2.82 Å. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(4), one O(7), and one O(8) atom. The Mg(1)-O(1) bond length is 2.08 Å. The Mg(1)-O(4) bond length is 2.02 Å. The Mg(1)-O(7) bond length is 1.95 Å. The Mg(1)-O(8) bond length is 2.01 Å. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form SbO6 octahedra that share corners with two equivalent K(2)O4 tetrahedra,  a cornercorner with one K(4)O5 trigonal bipyramid, and  an edgeedge with one K(4)O5 trigonal bipyramid. The Sb(1)-O(1) bond length is 2.03 Å. The Sb(1)-O(2) bond length is 2.13 Å. The Sb(1)-O(3) bond length is 1.98 Å. The Sb(1)-O(4) bond length is 2.14 Å. The Sb(1)-O(7) bond length is 2.05 Å. The Sb(1)-O(8) bond length is 2.08 Å. In the second Sb site, Sb(2) is bonded in a distorted trigonal non-coplanar geometry to one O(2), one O(5), and one O(6) atom. The Sb(2)-O(2) bond length is 2.04 Å. The Sb(2)-O(5) bond length is 1.97 Å. The Sb(2)-O(6) bond length is 1.98 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one K(4), one K(5), one K(6), one Mg(1), and one Sb(1) atom. In the second O site, O(2) is bonded to one K(4), one K(5), one K(6), one Sb(1), and one Sb(2) atom to form distorted edge-sharing OK3Sb2 trigonal bipyramids. In the third O site, O(3) is bonded to one K(1), one K(2), one K(3), one K(5), and one Sb(1) atom to form distorted edge-sharing OK4Sb trigonal bipyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one K(1), one K(2), one K(4), one Mg(1), and one Sb(1) atom. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one K(1), one K(2), one K(3), one K(4), one K(6), and one Sb(2) atom. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one K(1), one K(2), one K(3), one K(4), one K(5), and one Sb(2) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one K(1), one K(3), one K(6), one Mg(1), and one Sb(1) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one K(3), one K(5), one K(6), one Mg(1), and one Sb(1) atom.