Li2Ni3(P2O7)2 crystallizes in the triclinic P-1 space group. Li(1) is bonded in a rectangular see-saw-like geometry to one O(3), one O(4), one O(6), and one O(7) atom. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with two equivalent Ni(2)O5 square pyramids, corners with two equivalent P(1)O4 tetrahedra, and corners with four equivalent P(2)O4 tetrahedra. In the second Ni site, Ni(2) is bonded to one O(1), one O(3), one O(6), and two equivalent O(2) atoms to form NiO5 square pyramids that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Ni(2)O5 square pyramid. The corner-sharing octahedral tilt angles are 66°. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), 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 three equivalent Ni(2)O5 square pyramids, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ni(2)O5 square pyramids, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-61°. There are seven inequivalent O sites. In the first O site, O(1) 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(2) is bonded in a distorted trigonal planar geometry to two equivalent Ni(2) and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(2), and one P(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Li(1), one Ni(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(2), 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.
Li2Ni3(P2O7)2 crystallizes in the triclinic P-1 space group. Li(1) is bonded in a rectangular see-saw-like geometry to one O(3), one O(4), one O(6), and one O(7) atom. The Li(1)-O(3) bond length is 2.07 Å. The Li(1)-O(4) bond length is 2.02 Å. The Li(1)-O(6) bond length is 2.07 Å. The Li(1)-O(7) bond length is 1.94 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with two equivalent Ni(2)O5 square pyramids, corners with two equivalent P(1)O4 tetrahedra, and corners with four equivalent P(2)O4 tetrahedra. Both Ni(1)-O(1) bond lengths are 2.24 Å. Both Ni(1)-O(4) bond lengths are 2.17 Å. Both Ni(1)-O(7) bond lengths are 2.06 Å. In the second Ni site, Ni(2) is bonded to one O(1), one O(3), one O(6), and two equivalent O(2) atoms to form NiO5 square pyramids that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Ni(2)O5 square pyramid. The corner-sharing octahedral tilt angles are 66°. The Ni(2)-O(1) bond length is 2.08 Å. The Ni(2)-O(3) bond length is 2.02 Å. The Ni(2)-O(6) bond length is 2.08 Å. There is one shorter (2.02 Å) and one longer (2.07 Å) Ni(2)-O(2) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), 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 three equivalent Ni(2)O5 square pyramids, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. The P(1)-O(2) bond length is 1.55 Å. The P(1)-O(4) bond length is 1.52 Å. The P(1)-O(5) bond length is 1.62 Å. The P(1)-O(6) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ni(2)O5 square pyramids, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-61°. The P(2)-O(1) bond length is 1.55 Å. The P(2)-O(3) bond length is 1.52 Å. The P(2)-O(5) bond length is 1.62 Å. The P(2)-O(7) bond length is 1.53 Å. There are seven inequivalent O sites. In the first O site, O(1) 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(2) is bonded in a distorted trigonal planar geometry to two equivalent Ni(2) and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(2), and one P(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Li(1), one Ni(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(2), 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.