KCu2H3(SO5)2 crystallizes in the monoclinic Cm space group. K(1) is bonded to one O(3), one O(4), one O(7), one O(8), two equivalent O(1), and two equivalent O(2) atoms to form distorted KO8 hexagonal bipyramids that share corners with two equivalent S(1)O4 tetrahedra, corners with two equivalent S(2)O4 tetrahedra, edges with four equivalent Cu(1)O6 octahedra,  an edgeedge with one S(1)O4 tetrahedra, and  an edgeedge with one S(2)O4 tetrahedra. Cu(1) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form CuO6 octahedra that share corners with two equivalent S(1)O4 tetrahedra, corners with two equivalent S(2)O4 tetrahedra, edges with two equivalent K(1)O8 hexagonal bipyramids, and edges with two equivalent Cu(1)O6 octahedra. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(5) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(6) atom. In the third H site, H(3) is bonded in a linear geometry to one O(5) and one O(6) atom. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(3), one O(7), and two equivalent O(1) atoms to form SO4 tetrahedra that share corners with two equivalent K(1)O8 hexagonal bipyramids, corners with four equivalent Cu(1)O6 octahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. The corner-sharing octahedral tilt angles range from 43-48°. In the second S site, S(2) is bonded to one O(4), one O(8), and two equivalent O(2) atoms to form SO4 tetrahedra that share corners with two equivalent K(1)O8 hexagonal bipyramids, corners with four equivalent Cu(1)O6 octahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. The corner-sharing octahedral tilt angles range from 45-49°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one K(1), one Cu(1), and one S(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one K(1), one Cu(1), and one S(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one K(1) and one S(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1) and one S(2) atom. In the fifth O site, O(5) is bonded in a distorted water-like geometry to two equivalent Cu(1), one H(1), and one H(3) atom. In the sixth O site, O(6) is bonded in a distorted tetrahedral geometry to two equivalent Cu(1), one H(2), and one H(3) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one K(1), two equivalent Cu(1), and one S(1) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(1), two equivalent Cu(1), and one S(2) atom.
KCu2H3(SO5)2 crystallizes in the monoclinic Cm space group. K(1) is bonded to one O(3), one O(4), one O(7), one O(8), two equivalent O(1), and two equivalent O(2) atoms to form distorted KO8 hexagonal bipyramids that share corners with two equivalent S(1)O4 tetrahedra, corners with two equivalent S(2)O4 tetrahedra, edges with four equivalent Cu(1)O6 octahedra,  an edgeedge with one S(1)O4 tetrahedra, and  an edgeedge with one S(2)O4 tetrahedra. The K(1)-O(3) bond length is 2.87 Å. The K(1)-O(4) bond length is 2.87 Å. The K(1)-O(7) bond length is 2.75 Å. The K(1)-O(8) bond length is 2.75 Å. Both K(1)-O(1) bond lengths are 2.82 Å. Both K(1)-O(2) bond lengths are 2.82 Å. Cu(1) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form CuO6 octahedra that share corners with two equivalent S(1)O4 tetrahedra, corners with two equivalent S(2)O4 tetrahedra, edges with two equivalent K(1)O8 hexagonal bipyramids, and edges with two equivalent Cu(1)O6 octahedra. The Cu(1)-O(1) bond length is 1.98 Å. The Cu(1)-O(2) bond length is 1.97 Å. The Cu(1)-O(5) bond length is 2.06 Å. The Cu(1)-O(6) bond length is 1.98 Å. The Cu(1)-O(7) bond length is 2.42 Å. The Cu(1)-O(8) bond length is 2.43 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(5) atom. The H(1)-O(5) bond length is 0.99 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(6) atom. The H(2)-O(6) bond length is 0.99 Å. In the third H site, H(3) is bonded in a linear geometry to one O(5) and one O(6) atom. The H(3)-O(5) bond length is 1.08 Å. The H(3)-O(6) bond length is 1.42 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(3), one O(7), and two equivalent O(1) atoms to form SO4 tetrahedra that share corners with two equivalent K(1)O8 hexagonal bipyramids, corners with four equivalent Cu(1)O6 octahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. The corner-sharing octahedral tilt angles range from 43-48°. The S(1)-O(3) bond length is 1.46 Å. The S(1)-O(7) bond length is 1.49 Å. Both S(1)-O(1) bond lengths are 1.51 Å. In the second S site, S(2) is bonded to one O(4), one O(8), and two equivalent O(2) atoms to form SO4 tetrahedra that share corners with two equivalent K(1)O8 hexagonal bipyramids, corners with four equivalent Cu(1)O6 octahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. The corner-sharing octahedral tilt angles range from 45-49°. The S(2)-O(4) bond length is 1.46 Å. The S(2)-O(8) bond length is 1.49 Å. Both S(2)-O(2) bond lengths are 1.51 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one K(1), one Cu(1), and one S(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one K(1), one Cu(1), and one S(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one K(1) and one S(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1) and one S(2) atom. In the fifth O site, O(5) is bonded in a distorted water-like geometry to two equivalent Cu(1), one H(1), and one H(3) atom. In the sixth O site, O(6) is bonded in a distorted tetrahedral geometry to two equivalent Cu(1), one H(2), and one H(3) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one K(1), two equivalent Cu(1), and one S(1) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(1), two equivalent Cu(1), and one S(2) atom.