KNiPH2O5 crystallizes in the orthorhombic Pmn2_1 space group. K(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), two equivalent O(4), and four equivalent O(2) atoms. Ni(1) is bonded to one O(1), one O(3), and four equivalent O(4) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. P(1) is bonded to one O(1), one O(2), and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-56°. H(1) is bonded in a single-bond geometry to one O(3) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one K(1), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to four equivalent K(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one K(1), one Ni(1), and two equivalent H(1) atoms. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one K(1), two equivalent Ni(1), and one P(1) atom.
KNiPH2O5 crystallizes in the orthorhombic Pmn2_1 space group. K(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), two equivalent O(4), and four equivalent O(2) atoms. The K(1)-O(1) bond length is 3.11 Å. The K(1)-O(3) bond length is 2.90 Å. Both K(1)-O(4) bond lengths are 3.22 Å. There are a spread of K(1)-O(2) bond distances ranging from 2.69-2.86 Å. Ni(1) is bonded to one O(1), one O(3), and four equivalent O(4) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. The Ni(1)-O(1) bond length is 2.04 Å. The Ni(1)-O(3) bond length is 2.13 Å. There are two shorter (2.08 Å) and two longer (2.18 Å) Ni(1)-O(4) bond lengths. P(1) is bonded to one O(1), one O(2), and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-56°. The P(1)-O(1) bond length is 1.54 Å. The P(1)-O(2) bond length is 1.53 Å. Both P(1)-O(4) bond lengths are 1.59 Å. H(1) is bonded in a single-bond geometry to one O(3) atom. The H(1)-O(3) bond length is 0.99 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one K(1), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to four equivalent K(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one K(1), one Ni(1), and two equivalent H(1) atoms. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one K(1), two equivalent Ni(1), and one P(1) atom.