NiP2O7 crystallizes in the monoclinic C2/c space group. Ni(1) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-49°. In the second P site, P(2) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-49°. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(2) atom. In the second O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. In the third O site, O(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the fourth O site, O(2) is bonded in a bent 150 degrees geometry to one Ni(1) and one P(2) atom. In the fifth O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ni(1) and one P(2) atom. In the sixth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. In the seventh O site, O(5) is bonded in a bent 150 degrees geometry to one Ni(1) and one P(1) atom.
NiP2O7 crystallizes in the monoclinic C2/c space group. Ni(1) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. The Ni(1)-O(2) bond length is 2.03 Å. The Ni(1)-O(3) bond length is 2.07 Å. The Ni(1)-O(4) bond length is 2.06 Å. The Ni(1)-O(5) bond length is 2.05 Å. The Ni(1)-O(6) bond length is 2.08 Å. The Ni(1)-O(7) bond length is 2.06 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-49°. The P(1)-O(1) bond length is 1.61 Å. The P(1)-O(4) bond length is 1.54 Å. The P(1)-O(5) bond length is 1.51 Å. The P(1)-O(7) bond length is 1.53 Å. In the second P site, P(2) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-49°. The P(2)-O(1) bond length is 1.61 Å. The P(2)-O(2) bond length is 1.51 Å. The P(2)-O(3) bond length is 1.52 Å. The P(2)-O(6) bond length is 1.54 Å. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(2) atom. In the second O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. In the third O site, O(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the fourth O site, O(2) is bonded in a bent 150 degrees geometry to one Ni(1) and one P(2) atom. In the fifth O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ni(1) and one P(2) atom. In the sixth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. In the seventh O site, O(5) is bonded in a bent 150 degrees geometry to one Ni(1) and one P(1) atom.