LiNiP2O7 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), one O(6), and one O(7) atom. Ni(1) is bonded to one O(1), one O(2), one O(3), 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(6) 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 40-59°. In the second P site, P(2) is bonded to one O(2), one O(3), one O(4), 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(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-58°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a 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 trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Li(1), one P(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom.
LiNiP2O7 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), one O(6), and one O(7) atom. The Li(1)-O(1) bond length is 2.26 Å. The Li(1)-O(3) bond length is 2.30 Å. The Li(1)-O(4) bond length is 2.55 Å. The Li(1)-O(6) bond length is 2.03 Å. The Li(1)-O(7) bond length is 2.53 Å. Ni(1) is bonded to one O(1), one O(2), one O(3), 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(1) bond length is 2.07 Å. The Ni(1)-O(2) bond length is 1.96 Å. The Ni(1)-O(3) bond length is 2.13 Å. The Ni(1)-O(5) bond length is 2.03 Å. The Ni(1)-O(6) bond length is 2.04 Å. The Ni(1)-O(7) bond length is 1.99 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(6) 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 40-59°. The P(1)-O(1) bond length is 1.54 Å. The P(1)-O(4) bond length is 1.63 Å. The P(1)-O(5) bond length is 1.53 Å. The P(1)-O(6) bond length is 1.52 Å. In the second P site, P(2) is bonded to one O(2), one O(3), one O(4), 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(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-58°. The P(2)-O(2) bond length is 1.52 Å. The P(2)-O(3) bond length is 1.53 Å. The P(2)-O(4) bond length is 1.61 Å. The P(2)-O(7) bond length is 1.54 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a 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 trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Li(1), one P(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom.