NiPO4 crystallizes in the trigonal P31c space group. Ni(1) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted NiO5 trigonal bipyramids that share  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and edges with two equivalent Ni(1)O5 trigonal bipyramids. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(4) and three equivalent O(3) atoms to form PO4 tetrahedra that share corners with three equivalent Ni(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(5) and three equivalent O(2) atoms to form PO4 tetrahedra that share corners with six equivalent Ni(1)O5 trigonal bipyramids. In the third P site, P(3) is bonded to one O(6) and three equivalent O(1) atoms to form PO4 tetrahedra that share corners with six equivalent Ni(1)O5 trigonal bipyramids. There are six 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(3) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Ni(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one P(1) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to three equivalent Ni(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Ni(1) and one P(3) atom.
NiPO4 crystallizes in the trigonal P31c space group. Ni(1) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted NiO5 trigonal bipyramids that share  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and edges with two equivalent Ni(1)O5 trigonal bipyramids. The Ni(1)-O(1) bond length is 1.91 Å. The Ni(1)-O(2) bond length is 1.87 Å. The Ni(1)-O(3) bond length is 1.88 Å. The Ni(1)-O(5) bond length is 2.21 Å. The Ni(1)-O(6) bond length is 2.15 Å. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(4) and three equivalent O(3) atoms to form PO4 tetrahedra that share corners with three equivalent Ni(1)O5 trigonal bipyramids. The P(1)-O(4) bond length is 1.52 Å. All P(1)-O(3) bond lengths are 1.56 Å. In the second P site, P(2) is bonded to one O(5) and three equivalent O(2) atoms to form PO4 tetrahedra that share corners with six equivalent Ni(1)O5 trigonal bipyramids. The P(2)-O(5) bond length is 1.60 Å. All P(2)-O(2) bond lengths are 1.54 Å. In the third P site, P(3) is bonded to one O(6) and three equivalent O(1) atoms to form PO4 tetrahedra that share corners with six equivalent Ni(1)O5 trigonal bipyramids. The P(3)-O(6) bond length is 1.62 Å. All P(3)-O(1) bond lengths are 1.53 Å. There are six 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(3) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Ni(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one P(1) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to three equivalent Ni(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Ni(1) and one P(3) atom.