KFeH5(SO5)2 crystallizes in the triclinic P1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one O(14), one O(15), one O(18), one O(19), one O(5), one O(6), one O(7), and one O(8) atom. In the second K site, K(2) is bonded in a 8-coordinate geometry to one O(13), one O(16), one O(17), one O(20), one O(5), one O(6), one O(7), and one O(8) atom. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(10), one O(11), one O(17), one O(2), one O(20), and one O(3) atom to form FeO6 octahedra that share  a cornercorner with one S(1)O4 tetrahedra,  a cornercorner with one S(2)O4 tetrahedra,  a cornercorner with one S(3)O4 tetrahedra, and  a cornercorner with one S(4)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to one O(1), one O(12), one O(18), one O(19), one O(4), and one O(9) atom to form FeO6 octahedra that share  a cornercorner with one S(1)O4 tetrahedra,  a cornercorner with one S(2)O4 tetrahedra,  a cornercorner with one S(3)O4 tetrahedra, and  a cornercorner with one S(4)O4 tetrahedra. There are ten inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(2) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(3) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(4) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(1) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(2) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one O(3) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one O(4) atom. In the ninth H site, H(9) is bonded in a linear geometry to one O(5) and one O(7) atom. In the tenth H site, H(10) is bonded in a linear geometry to one O(6) and one O(8) atom. There are four inequivalent S sites. In the first S site, S(1) is bonded to one O(13), one O(17), one O(5), and one O(9) atom to form SO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra and  a cornercorner with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-48°. In the second S site, S(2) is bonded to one O(10), one O(14), one O(18), and one O(6) atom to form SO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra and  a cornercorner with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-48°. In the third S site, S(3) is bonded to one O(11), one O(15), one O(19), and one O(7) atom to form SO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra and  a cornercorner with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 47°. In the fourth S site, S(4) is bonded to one O(12), one O(16), one O(20), and one O(8) atom to form SO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra and  a cornercorner with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are twenty inequivalent O sites. In the first O site, O(1) is bonded in a distorted water-like geometry to one Fe(2), one H(1), and one H(5) atom. In the second O site, O(2) is bonded in a distorted water-like geometry to one Fe(1), one H(2), and one H(6) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one Fe(1), one H(3), and one H(7) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one Fe(2), one H(4), and one H(8) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one H(9), and one S(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one H(10), and one S(2) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one K(1), one K(2), one H(9), and one S(3) atom. In the eighth O site, O(8) is bonded in a bent 120 degrees geometry to one K(1), one K(2), one H(10), and one S(4) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one S(1) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one S(2) atom. In the eleventh O site, O(11) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one S(3) atom. In the twelfth O site, O(12) is bonded in a distorted bent 120 degrees geometry to one Fe(2) and one S(4) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one K(2) and one S(1) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one K(1) and one S(2) atom. In the fifteenth O site, O(15) is bonded in a distorted single-bond geometry to one K(1) and one S(3) atom. In the sixteenth O site, O(16) is bonded in a distorted single-bond geometry to one K(2) and one S(4) atom. In the seventeenth O site, O(17) is bonded in a 3-coordinate geometry to one K(2), one Fe(1), and one S(1) atom. In the eighteenth O site, O(18) is bonded in a 3-coordinate geometry to one K(1), one Fe(2), and one S(2) atom. In the nineteenth O site, O(19) is bonded in a 3-coordinate geometry to one K(1), one Fe(2), and one S(3) atom. In the twentieth O site, O(20) is bonded in a 3-coordinate geometry to one K(2), one Fe(1), and one S(4) atom.
KFeH5(SO5)2 crystallizes in the triclinic P1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one O(14), one O(15), one O(18), one O(19), one O(5), one O(6), one O(7), and one O(8) atom. The K(1)-O(14) bond length is 2.85 Å. The K(1)-O(15) bond length is 2.86 Å. The K(1)-O(18) bond length is 2.83 Å. The K(1)-O(19) bond length is 2.75 Å. The K(1)-O(5) bond length is 3.22 Å. The K(1)-O(6) bond length is 3.14 Å. The K(1)-O(7) bond length is 3.18 Å. The K(1)-O(8) bond length is 3.13 Å. In the second K site, K(2) is bonded in a 8-coordinate geometry to one O(13), one O(16), one O(17), one O(20), one O(5), one O(6), one O(7), and one O(8) atom. The K(2)-O(13) bond length is 2.85 Å. The K(2)-O(16) bond length is 2.86 Å. The K(2)-O(17) bond length is 2.84 Å. The K(2)-O(20) bond length is 2.75 Å. The K(2)-O(5) bond length is 3.14 Å. The K(2)-O(6) bond length is 3.23 Å. The K(2)-O(7) bond length is 3.13 Å. The K(2)-O(8) bond length is 3.18 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(10), one O(11), one O(17), one O(2), one O(20), and one O(3) atom to form FeO6 octahedra that share  a cornercorner with one S(1)O4 tetrahedra,  a cornercorner with one S(2)O4 tetrahedra,  a cornercorner with one S(3)O4 tetrahedra, and  a cornercorner with one S(4)O4 tetrahedra. The Fe(1)-O(10) bond length is 2.16 Å. The Fe(1)-O(11) bond length is 2.12 Å. The Fe(1)-O(17) bond length is 2.17 Å. The Fe(1)-O(2) bond length is 2.16 Å. The Fe(1)-O(20) bond length is 2.13 Å. The Fe(1)-O(3) bond length is 2.15 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(12), one O(18), one O(19), one O(4), and one O(9) atom to form FeO6 octahedra that share  a cornercorner with one S(1)O4 tetrahedra,  a cornercorner with one S(2)O4 tetrahedra,  a cornercorner with one S(3)O4 tetrahedra, and  a cornercorner with one S(4)O4 tetrahedra. The Fe(2)-O(1) bond length is 2.16 Å. The Fe(2)-O(12) bond length is 2.12 Å. The Fe(2)-O(18) bond length is 2.18 Å. The Fe(2)-O(19) bond length is 2.13 Å. The Fe(2)-O(4) bond length is 2.15 Å. The Fe(2)-O(9) bond length is 2.16 Å. There are ten inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. The H(1)-O(1) bond length is 0.99 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(2) atom. The H(2)-O(2) bond length is 0.99 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(3) atom. The H(3)-O(3) bond length is 0.99 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(4) atom. The H(4)-O(4) bond length is 0.99 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(1) atom. The H(5)-O(1) bond length is 0.98 Å. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(2) atom. The H(6)-O(2) bond length is 0.98 Å. In the seventh H site, H(7) is bonded in a single-bond geometry to one O(3) atom. The H(7)-O(3) bond length is 0.98 Å. In the eighth H site, H(8) is bonded in a single-bond geometry to one O(4) atom. The H(8)-O(4) bond length is 0.98 Å. In the ninth H site, H(9) is bonded in a linear geometry to one O(5) and one O(7) atom. The H(9)-O(5) bond length is 1.09 Å. The H(9)-O(7) bond length is 1.38 Å. In the tenth H site, H(10) is bonded in a linear geometry to one O(6) and one O(8) atom. The H(10)-O(6) bond length is 1.10 Å. The H(10)-O(8) bond length is 1.37 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded to one O(13), one O(17), one O(5), and one O(9) atom to form SO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra and  a cornercorner with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-48°. The S(1)-O(13) bond length is 1.47 Å. The S(1)-O(17) bond length is 1.48 Å. The S(1)-O(5) bond length is 1.56 Å. The S(1)-O(9) bond length is 1.48 Å. In the second S site, S(2) is bonded to one O(10), one O(14), one O(18), and one O(6) atom to form SO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra and  a cornercorner with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-48°. The S(2)-O(10) bond length is 1.48 Å. The S(2)-O(14) bond length is 1.47 Å. The S(2)-O(18) bond length is 1.48 Å. The S(2)-O(6) bond length is 1.56 Å. In the third S site, S(3) is bonded to one O(11), one O(15), one O(19), and one O(7) atom to form SO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra and  a cornercorner with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 47°. The S(3)-O(11) bond length is 1.49 Å. The S(3)-O(15) bond length is 1.48 Å. The S(3)-O(19) bond length is 1.49 Å. The S(3)-O(7) bond length is 1.51 Å. In the fourth S site, S(4) is bonded to one O(12), one O(16), one O(20), and one O(8) atom to form SO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra and  a cornercorner with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 47°. The S(4)-O(12) bond length is 1.49 Å. The S(4)-O(16) bond length is 1.48 Å. The S(4)-O(20) bond length is 1.49 Å. The S(4)-O(8) bond length is 1.51 Å. There are twenty inequivalent O sites. In the first O site, O(1) is bonded in a distorted water-like geometry to one Fe(2), one H(1), and one H(5) atom. In the second O site, O(2) is bonded in a distorted water-like geometry to one Fe(1), one H(2), and one H(6) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one Fe(1), one H(3), and one H(7) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one Fe(2), one H(4), and one H(8) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one H(9), and one S(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one H(10), and one S(2) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one K(1), one K(2), one H(9), and one S(3) atom. In the eighth O site, O(8) is bonded in a bent 120 degrees geometry to one K(1), one K(2), one H(10), and one S(4) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one S(1) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one S(2) atom. In the eleventh O site, O(11) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one S(3) atom. In the twelfth O site, O(12) is bonded in a distorted bent 120 degrees geometry to one Fe(2) and one S(4) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one K(2) and one S(1) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one K(1) and one S(2) atom. In the fifteenth O site, O(15) is bonded in a distorted single-bond geometry to one K(1) and one S(3) atom. In the sixteenth O site, O(16) is bonded in a distorted single-bond geometry to one K(2) and one S(4) atom. In the seventeenth O site, O(17) is bonded in a 3-coordinate geometry to one K(2), one Fe(1), and one S(1) atom. In the eighteenth O site, O(18) is bonded in a 3-coordinate geometry to one K(1), one Fe(2), and one S(2) atom. In the nineteenth O site, O(19) is bonded in a 3-coordinate geometry to one K(1), one Fe(2), and one S(3) atom. In the twentieth O site, O(20) is bonded in a 3-coordinate geometry to one K(2), one Fe(1), and one S(4) atom.