K3CaP2HO8 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 12-coordinate geometry to two equivalent H(1), two equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms. In the second K site, K(2) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(1), and six equivalent O(3) atoms. Ca(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form CaO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-35°. H(1) is bonded in a linear geometry to two equivalent K(1) and two equivalent O(2) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one K(1), two equivalent K(2), one Ca(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(2), two equivalent K(1), one P(1), and one H(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one K(1), three equivalent K(2), one Ca(1), and one P(1) atom.
K3CaP2HO8 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 12-coordinate geometry to two equivalent H(1), two equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms. Both K(1)-H(1) bond lengths are 2.91 Å. Both K(1)-O(1) bond lengths are 2.92 Å. All K(1)-O(2) bond lengths are 3.15 Å. All K(1)-O(3) bond lengths are 3.06 Å. In the second K site, K(2) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(1), and six equivalent O(3) atoms. The K(2)-O(2) bond length is 2.71 Å. Both K(2)-O(1) bond lengths are 2.92 Å. There are a spread of K(2)-O(3) bond distances ranging from 2.84-3.04 Å. Ca(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form CaO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. Both Ca(1)-O(1) bond lengths are 2.38 Å. All Ca(1)-O(3) bond lengths are 2.35 Å. P(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-35°. The P(1)-O(1) bond length is 1.55 Å. The P(1)-O(2) bond length is 1.58 Å. Both P(1)-O(3) bond lengths are 1.55 Å. H(1) is bonded in a linear geometry to two equivalent K(1) and two equivalent O(2) atoms. Both H(1)-O(2) bond lengths are 1.22 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one K(1), two equivalent K(2), one Ca(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(2), two equivalent K(1), one P(1), and one H(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one K(1), three equivalent K(2), one Ca(1), and one P(1) atom.