K4MgMn4O8 crystallizes in the triclinic P1 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to one O(1), one O(6), and two equivalent O(5) atoms. In the second K site, K(2) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(4), and two equivalent O(7) atoms. In the third K site, K(3) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(2), and two equivalent O(6) atoms. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to one O(4), one O(7), two equivalent O(3), and two equivalent O(8) atoms. Mg(1) is bonded in a trigonal planar geometry to one O(3) and two equivalent O(1) atoms. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(6), and two equivalent O(5) atoms to form distorted MnO4 trigonal pyramids that share corners with two equivalent Mn(1)O4 trigonal pyramids and edges with two equivalent Mn(2)O5 square pyramids. In the second Mn site, Mn(2) is bonded to one O(5), two equivalent O(2), and two equivalent O(6) atoms to form MnO5 square pyramids that share edges with two equivalent Mn(2)O5 square pyramids and edges with two equivalent Mn(1)O4 trigonal pyramids. In the third Mn site, Mn(3) is bonded to one O(7), two equivalent O(3), and two equivalent O(8) atoms to form edge-sharing MnO5 square pyramids. In the fourth Mn site, Mn(4) is bonded to one O(8), two equivalent O(4), and two equivalent O(7) atoms to form edge-sharing MnO5 square pyramids. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one K(1), two equivalent Mg(1), and one Mn(1) atom to form distorted OKMg2Mn tetrahedra that share corners with four equivalent O(5)K2Mn3 square pyramids and corners with two equivalent O(1)KMg2Mn tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to one K(2), two equivalent K(3), and two equivalent Mn(2) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to two equivalent K(4), one Mg(1), and two equivalent Mn(3) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one K(3), one K(4), two equivalent K(2), and two equivalent Mn(4) atoms. In the fifth O site, O(5) is bonded to two equivalent K(1), one Mn(2), and two equivalent Mn(1) atoms to form distorted OK2Mn3 square pyramids that share corners with four equivalent O(1)KMg2Mn tetrahedra and edges with two equivalent O(5)K2Mn3 square pyramids. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one K(1), two equivalent K(3), one Mn(1), and two equivalent Mn(2) atoms. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one K(4), two equivalent K(2), one Mn(3), and two equivalent Mn(4) atoms. In the eighth O site, O(8) is bonded to two equivalent K(4), one Mn(4), and two equivalent Mn(3) atoms to form edge-sharing OK2Mn3 square pyramids.
K4MgMn4O8 crystallizes in the triclinic P1 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to one O(1), one O(6), and two equivalent O(5) atoms. The K(1)-O(1) bond length is 2.71 Å. The K(1)-O(6) bond length is 2.98 Å. There is one shorter (2.53 Å) and one longer (2.55 Å) K(1)-O(5) bond length. In the second K site, K(2) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(4), and two equivalent O(7) atoms. The K(2)-O(2) bond length is 2.68 Å. Both K(2)-O(4) bond lengths are 2.72 Å. There is one shorter (2.83 Å) and one longer (2.90 Å) K(2)-O(7) bond length. In the third K site, K(3) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(2), and two equivalent O(6) atoms. The K(3)-O(4) bond length is 2.85 Å. There is one shorter (2.70 Å) and one longer (2.73 Å) K(3)-O(2) bond length. There is one shorter (2.83 Å) and one longer (2.86 Å) K(3)-O(6) bond length. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to one O(4), one O(7), two equivalent O(3), and two equivalent O(8) atoms. The K(4)-O(4) bond length is 3.01 Å. The K(4)-O(7) bond length is 2.91 Å. There is one shorter (2.78 Å) and one longer (2.82 Å) K(4)-O(3) bond length. There is one shorter (2.62 Å) and one longer (2.64 Å) K(4)-O(8) bond length. Mg(1) is bonded in a trigonal planar geometry to one O(3) and two equivalent O(1) atoms. The Mg(1)-O(3) bond length is 1.91 Å. Both Mg(1)-O(1) bond lengths are 1.90 Å. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(6), and two equivalent O(5) atoms to form distorted MnO4 trigonal pyramids that share corners with two equivalent Mn(1)O4 trigonal pyramids and edges with two equivalent Mn(2)O5 square pyramids. The Mn(1)-O(1) bond length is 2.06 Å. The Mn(1)-O(6) bond length is 2.16 Å. Both Mn(1)-O(5) bond lengths are 2.03 Å. In the second Mn site, Mn(2) is bonded to one O(5), two equivalent O(2), and two equivalent O(6) atoms to form MnO5 square pyramids that share edges with two equivalent Mn(2)O5 square pyramids and edges with two equivalent Mn(1)O4 trigonal pyramids. The Mn(2)-O(5) bond length is 2.21 Å. Both Mn(2)-O(2) bond lengths are 2.04 Å. There is one shorter (2.11 Å) and one longer (2.12 Å) Mn(2)-O(6) bond length. In the third Mn site, Mn(3) is bonded to one O(7), two equivalent O(3), and two equivalent O(8) atoms to form edge-sharing MnO5 square pyramids. The Mn(3)-O(7) bond length is 2.33 Å. There is one shorter (2.09 Å) and one longer (2.10 Å) Mn(3)-O(3) bond length. There is one shorter (2.04 Å) and one longer (2.05 Å) Mn(3)-O(8) bond length. In the fourth Mn site, Mn(4) is bonded to one O(8), two equivalent O(4), and two equivalent O(7) atoms to form edge-sharing MnO5 square pyramids. The Mn(4)-O(8) bond length is 2.17 Å. Both Mn(4)-O(4) bond lengths are 2.04 Å. Both Mn(4)-O(7) bond lengths are 2.06 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one K(1), two equivalent Mg(1), and one Mn(1) atom to form distorted OKMg2Mn tetrahedra that share corners with four equivalent O(5)K2Mn3 square pyramids and corners with two equivalent O(1)KMg2Mn tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to one K(2), two equivalent K(3), and two equivalent Mn(2) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to two equivalent K(4), one Mg(1), and two equivalent Mn(3) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one K(3), one K(4), two equivalent K(2), and two equivalent Mn(4) atoms. In the fifth O site, O(5) is bonded to two equivalent K(1), one Mn(2), and two equivalent Mn(1) atoms to form distorted OK2Mn3 square pyramids that share corners with four equivalent O(1)KMg2Mn tetrahedra and edges with two equivalent O(5)K2Mn3 square pyramids. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one K(1), two equivalent K(3), one Mn(1), and two equivalent Mn(2) atoms. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one K(4), two equivalent K(2), one Mn(3), and two equivalent Mn(4) atoms. In the eighth O site, O(8) is bonded to two equivalent K(4), one Mn(4), and two equivalent Mn(3) atoms to form edge-sharing OK2Mn3 square pyramids.