NiPO4 crystallizes in the orthorhombic Pnma space group. Ni(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with four equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. 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 four equivalent Ni(1)O6 octahedra and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Ni(1) and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one P(1) atom.
NiPO4 crystallizes in the orthorhombic Pnma space group. Ni(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with four equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. The Ni(1)-O(1) bond length is 2.00 Å. The Ni(1)-O(2) bond length is 1.98 Å. There are two shorter (2.04 Å) and two longer (2.14 Å) Ni(1)-O(3) bond lengths. 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 four equivalent Ni(1)O6 octahedra and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. 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(3) bond lengths are 1.57 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Ni(1) and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one P(1) atom.