Ni(PO3)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. In the second Ni site, Ni(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-59°. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, and corners with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-59°. There are six inequivalent O sites. In the first O site, O(3) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(2) atom. In the second O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the third O site, O(5) is bonded in a distorted bent 120 degrees geometry to one P(1) and one P(2) atom. In the fourth O site, O(6) is bonded in a bent 150 degrees geometry to one Ni(2) and one P(2) atom. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Ni(1) and one P(1) atom. In the sixth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(1) atom.
Ni(PO3)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. Both Ni(1)-O(1) bond lengths are 1.99 Å. Both Ni(1)-O(2) bond lengths are 2.10 Å. Both Ni(1)-O(3) bond lengths are 2.08 Å. In the second Ni site, Ni(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. Both Ni(2)-O(2) bond lengths are 2.07 Å. Both Ni(2)-O(3) bond lengths are 2.06 Å. Both Ni(2)-O(6) bond lengths are 1.99 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-59°. The P(1)-O(1) bond length is 1.46 Å. The P(1)-O(2) bond length is 1.51 Å. The P(1)-O(4) bond length is 1.60 Å. The P(1)-O(5) bond length is 1.59 Å. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, and corners with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-59°. The P(2)-O(3) bond length is 1.50 Å. The P(2)-O(4) bond length is 1.59 Å. The P(2)-O(5) bond length is 1.59 Å. The P(2)-O(6) bond length is 1.46 Å. There are six inequivalent O sites. In the first O site, O(3) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(2) atom. In the second O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the third O site, O(5) is bonded in a distorted bent 120 degrees geometry to one P(1) and one P(2) atom. In the fourth O site, O(6) is bonded in a bent 150 degrees geometry to one Ni(2) and one P(2) atom. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Ni(1) and one P(1) atom. In the sixth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(1) atom.