K4MgV6O16 crystallizes in the triclinic P1 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(12), one O(16), one O(3), one O(5), and one O(8) atom. In the second K site, K(2) is bonded to one O(1), one O(16), one O(4), one O(5), one O(7), and one O(9) atom to form distorted KO6 pentagonal pyramids that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(3)O4 tetrahedra, corners with two equivalent V(4)O4 tetrahedra,  a cornercorner with one V(6)O5 trigonal bipyramid,  an edgeedge with one V(1)O4 tetrahedra, and  an edgeedge with one V(6)O5 trigonal bipyramid. In the third K site, K(3) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(15), one O(4), one O(6), one O(7), and one O(8) atom. In the fourth K site, K(4) is bonded in a 8-coordinate geometry to one O(11), one O(13), one O(15), one O(2), one O(3), one O(5), one O(6), and one O(8) atom. Mg(1) is bonded to one O(11), one O(12), one O(2), and one O(7) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one K(2)O6 pentagonal pyramid,  a cornercorner with one V(2)O4 tetrahedra, corners with two equivalent V(1)O4 tetrahedra,  a cornercorner with one V(5)O5 trigonal bipyramid, and  an edgeedge with one V(5)O5 trigonal bipyramid. There are six inequivalent V sites. In the first V site, V(1) is bonded to one O(12), one O(16), one O(4), and one O(7) atom to form VO4 tetrahedra that share  a cornercorner with one K(2)O6 pentagonal pyramid,  a cornercorner with one V(3)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra,  a cornercorner with one V(5)O5 trigonal bipyramid,  a cornercorner with one V(6)O5 trigonal bipyramid, and  an edgeedge with one K(2)O6 pentagonal pyramid. In the second V site, V(2) is bonded to one O(10), one O(11), one O(3), and one O(8) atom to form VO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one V(4)O4 tetrahedra,  a cornercorner with one V(5)O5 trigonal bipyramid, and  a cornercorner with one V(6)O5 trigonal bipyramid. In the third V site, V(3) is bonded to one O(13), one O(15), one O(4), and one O(6) atom to form VO4 tetrahedra that share  a cornercorner with one K(2)O6 pentagonal pyramid,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(5)O5 trigonal bipyramid, and  a cornercorner with one V(6)O5 trigonal bipyramid. In the fourth V site, V(4) is bonded to one O(14), one O(3), one O(5), and one O(9) atom to form VO4 tetrahedra that share corners with two equivalent K(2)O6 pentagonal pyramids,  a cornercorner with one V(2)O4 tetrahedra,  a cornercorner with one V(5)O5 trigonal bipyramid, and  a cornercorner with one V(6)O5 trigonal bipyramid. In the fifth V site, V(5) is bonded to one O(11), one O(12), one O(13), one O(14), and one O(2) atom to form distorted VO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(2)O4 tetrahedra,  a cornercorner with one V(3)O4 tetrahedra,  a cornercorner with one V(4)O4 tetrahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. In the sixth V site, V(6) is bonded to one O(1), one O(10), one O(15), one O(16), and one O(9) atom to form distorted VO5 trigonal bipyramids that share  a cornercorner with one K(2)O6 pentagonal pyramid,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(2)O4 tetrahedra,  a cornercorner with one V(3)O4 tetrahedra,  a cornercorner with one V(4)O4 tetrahedra, and  an edgeedge with one K(2)O6 pentagonal pyramid. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one K(1), one K(2), one K(3), and one V(6) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one K(4), one Mg(1), and one V(5) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one K(1), one K(4), one V(2), and one V(4) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one K(2), one K(3), one V(1), and one V(3) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one K(1), one K(2), one K(4), and one V(4) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one K(3), one K(4), and one V(3) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one K(2), one K(3), one Mg(1), and one V(1) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(1), one K(3), one K(4), and one V(2) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one K(2), one V(4), and one V(6) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one K(1), one K(3), one V(2), and one V(6) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one K(4), one Mg(1), one V(2), and one V(5) atom. In the twelfth O site, O(12) is bonded in a distorted tetrahedral geometry to one K(1), one Mg(1), one V(1), and one V(5) atom. In the thirteenth O site, O(13) is bonded in a 2-coordinate geometry to one K(4), one V(3), and one V(5) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one V(4) and one V(5) atom. In the fifteenth O site, O(15) is bonded in a 4-coordinate geometry to one K(3), one K(4), one V(3), and one V(6) atom. In the sixteenth O site, O(16) is bonded in a 4-coordinate geometry to one K(1), one K(2), one V(1), and one V(6) atom.
K4MgV6O16 crystallizes in the triclinic P1 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(12), one O(16), one O(3), one O(5), and one O(8) atom. The K(1)-O(1) bond length is 3.30 Å. The K(1)-O(10) bond length is 2.93 Å. The K(1)-O(12) bond length is 2.68 Å. The K(1)-O(16) bond length is 2.76 Å. The K(1)-O(3) bond length is 2.89 Å. The K(1)-O(5) bond length is 2.94 Å. The K(1)-O(8) bond length is 2.88 Å. In the second K site, K(2) is bonded to one O(1), one O(16), one O(4), one O(5), one O(7), and one O(9) atom to form distorted KO6 pentagonal pyramids that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(3)O4 tetrahedra, corners with two equivalent V(4)O4 tetrahedra,  a cornercorner with one V(6)O5 trigonal bipyramid,  an edgeedge with one V(1)O4 tetrahedra, and  an edgeedge with one V(6)O5 trigonal bipyramid. The K(2)-O(1) bond length is 2.85 Å. The K(2)-O(16) bond length is 2.97 Å. The K(2)-O(4) bond length is 2.79 Å. The K(2)-O(5) bond length is 2.84 Å. The K(2)-O(7) bond length is 3.19 Å. The K(2)-O(9) bond length is 2.94 Å. In the third K site, K(3) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(15), one O(4), one O(6), one O(7), and one O(8) atom. The K(3)-O(1) bond length is 2.75 Å. The K(3)-O(10) bond length is 2.82 Å. The K(3)-O(15) bond length is 2.71 Å. The K(3)-O(4) bond length is 3.18 Å. The K(3)-O(6) bond length is 2.58 Å. The K(3)-O(7) bond length is 2.93 Å. The K(3)-O(8) bond length is 2.78 Å. In the fourth K site, K(4) is bonded in a 8-coordinate geometry to one O(11), one O(13), one O(15), one O(2), one O(3), one O(5), one O(6), and one O(8) atom. The K(4)-O(11) bond length is 3.08 Å. The K(4)-O(13) bond length is 2.88 Å. The K(4)-O(15) bond length is 2.98 Å. The K(4)-O(2) bond length is 3.02 Å. The K(4)-O(3) bond length is 2.85 Å. The K(4)-O(5) bond length is 3.09 Å. The K(4)-O(6) bond length is 2.69 Å. The K(4)-O(8) bond length is 3.06 Å. Mg(1) is bonded to one O(11), one O(12), one O(2), and one O(7) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one K(2)O6 pentagonal pyramid,  a cornercorner with one V(2)O4 tetrahedra, corners with two equivalent V(1)O4 tetrahedra,  a cornercorner with one V(5)O5 trigonal bipyramid, and  an edgeedge with one V(5)O5 trigonal bipyramid. The Mg(1)-O(11) bond length is 2.12 Å. The Mg(1)-O(12) bond length is 1.99 Å. The Mg(1)-O(2) bond length is 1.97 Å. The Mg(1)-O(7) bond length is 1.93 Å. There are six inequivalent V sites. In the first V site, V(1) is bonded to one O(12), one O(16), one O(4), and one O(7) atom to form VO4 tetrahedra that share  a cornercorner with one K(2)O6 pentagonal pyramid,  a cornercorner with one V(3)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra,  a cornercorner with one V(5)O5 trigonal bipyramid,  a cornercorner with one V(6)O5 trigonal bipyramid, and  an edgeedge with one K(2)O6 pentagonal pyramid. The V(1)-O(12) bond length is 2.03 Å. The V(1)-O(16) bond length is 1.92 Å. The V(1)-O(4) bond length is 1.97 Å. The V(1)-O(7) bond length is 1.83 Å. In the second V site, V(2) is bonded to one O(10), one O(11), one O(3), and one O(8) atom to form VO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one V(4)O4 tetrahedra,  a cornercorner with one V(5)O5 trigonal bipyramid, and  a cornercorner with one V(6)O5 trigonal bipyramid. The V(2)-O(10) bond length is 1.72 Å. The V(2)-O(11) bond length is 1.78 Å. The V(2)-O(3) bond length is 1.82 Å. The V(2)-O(8) bond length is 1.68 Å. In the third V site, V(3) is bonded to one O(13), one O(15), one O(4), and one O(6) atom to form VO4 tetrahedra that share  a cornercorner with one K(2)O6 pentagonal pyramid,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(5)O5 trigonal bipyramid, and  a cornercorner with one V(6)O5 trigonal bipyramid. The V(3)-O(13) bond length is 1.79 Å. The V(3)-O(15) bond length is 1.77 Å. The V(3)-O(4) bond length is 1.79 Å. The V(3)-O(6) bond length is 1.67 Å. In the fourth V site, V(4) is bonded to one O(14), one O(3), one O(5), and one O(9) atom to form VO4 tetrahedra that share corners with two equivalent K(2)O6 pentagonal pyramids,  a cornercorner with one V(2)O4 tetrahedra,  a cornercorner with one V(5)O5 trigonal bipyramid, and  a cornercorner with one V(6)O5 trigonal bipyramid. The V(4)-O(14) bond length is 1.73 Å. The V(4)-O(3) bond length is 1.85 Å. The V(4)-O(5) bond length is 1.67 Å. The V(4)-O(9) bond length is 1.73 Å. In the fifth V site, V(5) is bonded to one O(11), one O(12), one O(13), one O(14), and one O(2) atom to form distorted VO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(2)O4 tetrahedra,  a cornercorner with one V(3)O4 tetrahedra,  a cornercorner with one V(4)O4 tetrahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. The V(5)-O(11) bond length is 2.18 Å. The V(5)-O(12) bond length is 1.90 Å. The V(5)-O(13) bond length is 1.93 Å. The V(5)-O(14) bond length is 1.94 Å. The V(5)-O(2) bond length is 1.70 Å. In the sixth V site, V(6) is bonded to one O(1), one O(10), one O(15), one O(16), and one O(9) atom to form distorted VO5 trigonal bipyramids that share  a cornercorner with one K(2)O6 pentagonal pyramid,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(2)O4 tetrahedra,  a cornercorner with one V(3)O4 tetrahedra,  a cornercorner with one V(4)O4 tetrahedra, and  an edgeedge with one K(2)O6 pentagonal pyramid. The V(6)-O(1) bond length is 1.68 Å. The V(6)-O(10) bond length is 2.09 Å. The V(6)-O(15) bond length is 2.02 Å. The V(6)-O(16) bond length is 1.87 Å. The V(6)-O(9) bond length is 2.00 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one K(1), one K(2), one K(3), and one V(6) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one K(4), one Mg(1), and one V(5) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one K(1), one K(4), one V(2), and one V(4) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one K(2), one K(3), one V(1), and one V(3) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one K(1), one K(2), one K(4), and one V(4) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one K(3), one K(4), and one V(3) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one K(2), one K(3), one Mg(1), and one V(1) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(1), one K(3), one K(4), and one V(2) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one K(2), one V(4), and one V(6) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one K(1), one K(3), one V(2), and one V(6) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one K(4), one Mg(1), one V(2), and one V(5) atom. In the twelfth O site, O(12) is bonded in a distorted tetrahedral geometry to one K(1), one Mg(1), one V(1), and one V(5) atom. In the thirteenth O site, O(13) is bonded in a 2-coordinate geometry to one K(4), one V(3), and one V(5) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one V(4) and one V(5) atom. In the fifteenth O site, O(15) is bonded in a 4-coordinate geometry to one K(3), one K(4), one V(3), and one V(6) atom. In the sixteenth O site, O(16) is bonded in a 4-coordinate geometry to one K(1), one K(2), one V(1), and one V(6) atom.