K7Fe5O16 crystallizes in the monoclinic Pm space group. There are seven inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to two equivalent O(10) and two equivalent O(12) atoms. In the second K site, K(2) is bonded in a 6-coordinate geometry to two equivalent O(11), two equivalent O(2), and two equivalent O(9) atoms. In the third K site, K(3) is bonded in a 6-coordinate geometry to two equivalent O(10), two equivalent O(12), and two equivalent O(4) atoms. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to two equivalent O(11), two equivalent O(8), and two equivalent O(9) atoms. In the fifth K site, K(5) is bonded in a 6-coordinate geometry to one O(2), one O(5), two equivalent O(11), and two equivalent O(7) atoms. In the sixth K site, K(6) is bonded to one O(3), one O(8), two equivalent O(10), and two equivalent O(6) atoms to form distorted KO6 pentagonal pyramids that share corners with two equivalent K(6)O6 pentagonal pyramids,  a cornercorner with one Fe(3)O4 tetrahedra,  a cornercorner with one Fe(4)O4 tetrahedra, corners with two equivalent Fe(5)O4 tetrahedra, and edges with two equivalent Fe(2)O4 tetrahedra. In the seventh K site, K(7) is bonded in a 4-coordinate geometry to one O(4), one O(7), and two equivalent O(9) atoms. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(5), and two equivalent O(9) atoms to form corner-sharing FeO4 tetrahedra. In the second Fe site, Fe(2) is bonded to one O(2), one O(6), and two equivalent O(10) atoms to form FeO4 tetrahedra that share  a cornercorner with one Fe(5)O4 tetrahedra and edges with two equivalent K(6)O6 pentagonal pyramids. In the third Fe site, Fe(3) is bonded to one O(3), one O(7), and two equivalent O(11) atoms to form FeO4 tetrahedra that share  a cornercorner with one K(6)O6 pentagonal pyramid. In the fourth Fe site, Fe(4) is bonded to one O(4), one O(8), and two equivalent O(12) atoms to form FeO4 tetrahedra that share  a cornercorner with one K(6)O6 pentagonal pyramid and corners with two equivalent Fe(5)O4 tetrahedra. In the fifth Fe site, Fe(5) is bonded to one O(1), one O(6), and two equivalent O(12) atoms to form FeO4 tetrahedra that share corners with two equivalent K(6)O6 pentagonal pyramids,  a cornercorner with one Fe(1)O4 tetrahedra,  a cornercorner with one Fe(2)O4 tetrahedra, and corners with two equivalent Fe(4)O4 tetrahedra. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one Fe(5) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one K(5), two equivalent K(2), and one Fe(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one K(6) and one Fe(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one K(7), two equivalent K(3), and one Fe(4) atom. In the fifth O site, O(5) is bonded in a distorted linear geometry to one K(5) and one Fe(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent K(6), one Fe(2), and one Fe(5) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one K(7), two equivalent K(5), and one Fe(3) atom. In the eighth O site, O(8) is bonded in a 1-coordinate geometry to one K(6), two equivalent K(4), and one Fe(4) atom. In the ninth O site, O(9) is bonded to one K(2), one K(4), one K(7), and one Fe(1) atom to form a mixture of distorted edge and corner-sharing OK3Fe tetrahedra. In the tenth O site, O(10) is bonded to one K(1), one K(3), one K(6), and one Fe(2) atom to form distorted edge-sharing OK3Fe tetrahedra. In the eleventh O site, O(11) is bonded to one K(2), one K(4), one K(5), and one Fe(3) atom to form a mixture of distorted edge and corner-sharing OK3Fe tetrahedra. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to one K(1), one K(3), one Fe(4), and one Fe(5) atom.
K7Fe5O16 crystallizes in the monoclinic Pm space group. There are seven inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to two equivalent O(10) and two equivalent O(12) atoms. Both K(1)-O(10) bond lengths are 2.72 Å. Both K(1)-O(12) bond lengths are 3.02 Å. In the second K site, K(2) is bonded in a 6-coordinate geometry to two equivalent O(11), two equivalent O(2), and two equivalent O(9) atoms. Both K(2)-O(11) bond lengths are 2.75 Å. Both K(2)-O(2) bond lengths are 3.30 Å. Both K(2)-O(9) bond lengths are 2.75 Å. In the third K site, K(3) is bonded in a 6-coordinate geometry to two equivalent O(10), two equivalent O(12), and two equivalent O(4) atoms. Both K(3)-O(10) bond lengths are 2.78 Å. Both K(3)-O(12) bond lengths are 2.93 Å. Both K(3)-O(4) bond lengths are 3.10 Å. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to two equivalent O(11), two equivalent O(8), and two equivalent O(9) atoms. Both K(4)-O(11) bond lengths are 2.63 Å. Both K(4)-O(8) bond lengths are 3.36 Å. Both K(4)-O(9) bond lengths are 2.83 Å. In the fifth K site, K(5) is bonded in a 6-coordinate geometry to one O(2), one O(5), two equivalent O(11), and two equivalent O(7) atoms. The K(5)-O(2) bond length is 2.60 Å. The K(5)-O(5) bond length is 2.56 Å. Both K(5)-O(11) bond lengths are 2.62 Å. Both K(5)-O(7) bond lengths are 2.98 Å. In the sixth K site, K(6) is bonded to one O(3), one O(8), two equivalent O(10), and two equivalent O(6) atoms to form distorted KO6 pentagonal pyramids that share corners with two equivalent K(6)O6 pentagonal pyramids,  a cornercorner with one Fe(3)O4 tetrahedra,  a cornercorner with one Fe(4)O4 tetrahedra, corners with two equivalent Fe(5)O4 tetrahedra, and edges with two equivalent Fe(2)O4 tetrahedra. The K(6)-O(3) bond length is 2.58 Å. The K(6)-O(8) bond length is 2.78 Å. Both K(6)-O(10) bond lengths are 2.73 Å. Both K(6)-O(6) bond lengths are 3.09 Å. In the seventh K site, K(7) is bonded in a 4-coordinate geometry to one O(4), one O(7), and two equivalent O(9) atoms. The K(7)-O(4) bond length is 2.64 Å. The K(7)-O(7) bond length is 2.61 Å. Both K(7)-O(9) bond lengths are 2.64 Å. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(5), and two equivalent O(9) atoms to form corner-sharing FeO4 tetrahedra. The Fe(1)-O(1) bond length is 1.73 Å. The Fe(1)-O(5) bond length is 1.64 Å. Both Fe(1)-O(9) bond lengths are 1.66 Å. In the second Fe site, Fe(2) is bonded to one O(2), one O(6), and two equivalent O(10) atoms to form FeO4 tetrahedra that share  a cornercorner with one Fe(5)O4 tetrahedra and edges with two equivalent K(6)O6 pentagonal pyramids. The Fe(2)-O(2) bond length is 1.66 Å. The Fe(2)-O(6) bond length is 1.94 Å. Both Fe(2)-O(10) bond lengths are 1.70 Å. In the third Fe site, Fe(3) is bonded to one O(3), one O(7), and two equivalent O(11) atoms to form FeO4 tetrahedra that share  a cornercorner with one K(6)O6 pentagonal pyramid. The Fe(3)-O(3) bond length is 1.64 Å. The Fe(3)-O(7) bond length is 1.67 Å. Both Fe(3)-O(11) bond lengths are 1.66 Å. In the fourth Fe site, Fe(4) is bonded to one O(4), one O(8), and two equivalent O(12) atoms to form FeO4 tetrahedra that share  a cornercorner with one K(6)O6 pentagonal pyramid and corners with two equivalent Fe(5)O4 tetrahedra. The Fe(4)-O(4) bond length is 1.70 Å. The Fe(4)-O(8) bond length is 1.70 Å. Both Fe(4)-O(12) bond lengths are 1.85 Å. In the fifth Fe site, Fe(5) is bonded to one O(1), one O(6), and two equivalent O(12) atoms to form FeO4 tetrahedra that share corners with two equivalent K(6)O6 pentagonal pyramids,  a cornercorner with one Fe(1)O4 tetrahedra,  a cornercorner with one Fe(2)O4 tetrahedra, and corners with two equivalent Fe(4)O4 tetrahedra. The Fe(5)-O(1) bond length is 1.89 Å. The Fe(5)-O(6) bond length is 1.83 Å. Both Fe(5)-O(12) bond lengths are 1.87 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one Fe(5) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one K(5), two equivalent K(2), and one Fe(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one K(6) and one Fe(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one K(7), two equivalent K(3), and one Fe(4) atom. In the fifth O site, O(5) is bonded in a distorted linear geometry to one K(5) and one Fe(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent K(6), one Fe(2), and one Fe(5) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one K(7), two equivalent K(5), and one Fe(3) atom. In the eighth O site, O(8) is bonded in a 1-coordinate geometry to one K(6), two equivalent K(4), and one Fe(4) atom. In the ninth O site, O(9) is bonded to one K(2), one K(4), one K(7), and one Fe(1) atom to form a mixture of distorted edge and corner-sharing OK3Fe tetrahedra. In the tenth O site, O(10) is bonded to one K(1), one K(3), one K(6), and one Fe(2) atom to form distorted edge-sharing OK3Fe tetrahedra. In the eleventh O site, O(11) is bonded to one K(2), one K(4), one K(5), and one Fe(3) atom to form a mixture of distorted edge and corner-sharing OK3Fe tetrahedra. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to one K(1), one K(3), one Fe(4), and one Fe(5) atom.