KHSi2O5 crystallizes in the monoclinic C2/m space group. There are three inequivalent K sites. In the first K site, K(1) is bonded to four equivalent O(2) and four equivalent O(3) atoms to form distorted KO8 hexagonal bipyramids that share corners with four equivalent Si(1)O4 tetrahedra and edges with four equivalent Si(2)O4 tetrahedra. In the second K site, K(2) is bonded to four equivalent O(1) and four equivalent O(4) atoms to form distorted KO8 hexagonal bipyramids that share corners with four equivalent Si(2)O4 tetrahedra and edges with four equivalent Si(1)O4 tetrahedra. In the third K site, K(3) is bonded in a 8-coordinate geometry to two equivalent H(1), one O(5), one O(6), two equivalent O(1), and two equivalent O(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one K(1)O8 hexagonal bipyramid,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one K(2)O8 hexagonal bipyramid. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one K(2)O8 hexagonal bipyramid,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. H(1) is bonded in a linear geometry to one K(3), one O(1), and one O(2) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one K(2), one K(3), one Si(1), and one H(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(3), one Si(2), and one H(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one K(2), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one K(3) and two equivalent Si(2) atoms. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one K(3) and two equivalent Si(1) atoms.
KHSi2O5 crystallizes in the monoclinic C2/m space group. There are three inequivalent K sites. In the first K site, K(1) is bonded to four equivalent O(2) and four equivalent O(3) atoms to form distorted KO8 hexagonal bipyramids that share corners with four equivalent Si(1)O4 tetrahedra and edges with four equivalent Si(2)O4 tetrahedra. All K(1)-O(2) bond lengths are 2.86 Å. All K(1)-O(3) bond lengths are 3.06 Å. In the second K site, K(2) is bonded to four equivalent O(1) and four equivalent O(4) atoms to form distorted KO8 hexagonal bipyramids that share corners with four equivalent Si(2)O4 tetrahedra and edges with four equivalent Si(1)O4 tetrahedra. All K(2)-O(1) bond lengths are 2.94 Å. All K(2)-O(4) bond lengths are 3.08 Å. In the third K site, K(3) is bonded in a 8-coordinate geometry to two equivalent H(1), one O(5), one O(6), two equivalent O(1), and two equivalent O(2) atoms. Both K(3)-H(1) bond lengths are 2.93 Å. The K(3)-O(5) bond length is 3.17 Å. The K(3)-O(6) bond length is 3.11 Å. Both K(3)-O(1) bond lengths are 2.73 Å. Both K(3)-O(2) bond lengths are 2.89 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one K(1)O8 hexagonal bipyramid,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one K(2)O8 hexagonal bipyramid. The Si(1)-O(1) bond length is 1.59 Å. The Si(1)-O(3) bond length is 1.66 Å. The Si(1)-O(4) bond length is 1.65 Å. The Si(1)-O(6) bond length is 1.64 Å. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one K(2)O8 hexagonal bipyramid,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. The Si(2)-O(2) bond length is 1.62 Å. The Si(2)-O(3) bond length is 1.64 Å. The Si(2)-O(4) bond length is 1.63 Å. The Si(2)-O(5) bond length is 1.65 Å. H(1) is bonded in a linear geometry to one K(3), one O(1), and one O(2) atom. The H(1)-O(1) bond length is 1.36 Å. The H(1)-O(2) bond length is 1.10 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one K(2), one K(3), one Si(1), and one H(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(3), one Si(2), and one H(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one K(2), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one K(3) and two equivalent Si(2) atoms. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one K(3) and two equivalent Si(1) atoms.