Li2Ni3(P2O7)2 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(4) atoms. In the second Li site, Li(2) is bonded in a 5-coordinate geometry to one O(10), one O(12), one O(13), one O(14), and one O(6) atom. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(7) atom to form distorted NiO5 trigonal bipyramids that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. In the second Ni site, Ni(2) is bonded in a 5-coordinate geometry to one O(10), one O(11), one O(5), one O(6), and one O(9) atom. In the third Ni site, Ni(3) is bonded in a distorted see-saw-like geometry to one O(12), one O(13), one O(14), and one O(8) atom. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one Ni(1)O5 trigonal bipyramid, and  an edgeedge with one Ni(1)O5 trigonal bipyramid. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Ni(1)O5 trigonal bipyramids. In the third P site, P(3) is bonded to one O(11), one O(13), one O(7), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one P(4)O4 tetrahedra and  a cornercorner with one Ni(1)O5 trigonal bipyramid. In the fourth P site, P(4) is bonded to one O(10), one O(12), one O(14), and one O(9) atom to form corner-sharing PO4 tetrahedra. There are fourteen 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 T-shaped geometry to one Li(1), one Ni(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ni(1), one P(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Li(1), one Ni(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(2) and one P(2) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Li(2), one Ni(2), and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(3) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Ni(3) and one P(2) atom. In the ninth O site, O(9) is bonded in a distorted bent 120 degrees geometry to one Ni(2), one P(3), and one P(4) atom. In the tenth O site, O(10) is bonded in a distorted water-like geometry to one Li(2), one Ni(2), and one P(4) atom. In the eleventh O site, O(11) is bonded in a bent 120 degrees geometry to one Ni(2) and one P(3) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Li(2), one Ni(3), and one P(4) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Li(2), one Ni(3), and one P(3) atom. In the fourteenth O site, O(14) is bonded in a distorted trigonal planar geometry to one Li(2), one Ni(3), and one P(4) atom.
Li2Ni3(P2O7)2 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(4) atoms. The Li(1)-O(1) bond length is 2.07 Å. The Li(1)-O(2) bond length is 2.03 Å. There is one shorter (2.03 Å) and one longer (2.36 Å) Li(1)-O(4) bond length. In the second Li site, Li(2) is bonded in a 5-coordinate geometry to one O(10), one O(12), one O(13), one O(14), and one O(6) atom. The Li(2)-O(10) bond length is 2.67 Å. The Li(2)-O(12) bond length is 2.11 Å. The Li(2)-O(13) bond length is 2.50 Å. The Li(2)-O(14) bond length is 2.04 Å. The Li(2)-O(6) bond length is 2.63 Å. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(7) atom to form distorted NiO5 trigonal bipyramids that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The Ni(1)-O(1) bond length is 1.99 Å. The Ni(1)-O(2) bond length is 2.08 Å. The Ni(1)-O(3) bond length is 2.09 Å. The Ni(1)-O(4) bond length is 2.00 Å. The Ni(1)-O(7) bond length is 1.93 Å. In the second Ni site, Ni(2) is bonded in a 5-coordinate geometry to one O(10), one O(11), one O(5), one O(6), and one O(9) atom. The Ni(2)-O(10) bond length is 2.03 Å. The Ni(2)-O(11) bond length is 1.93 Å. The Ni(2)-O(5) bond length is 1.99 Å. The Ni(2)-O(6) bond length is 1.97 Å. The Ni(2)-O(9) bond length is 2.52 Å. In the third Ni site, Ni(3) is bonded in a distorted see-saw-like geometry to one O(12), one O(13), one O(14), and one O(8) atom. The Ni(3)-O(12) bond length is 2.02 Å. The Ni(3)-O(13) bond length is 1.94 Å. The Ni(3)-O(14) bond length is 2.05 Å. The Ni(3)-O(8) bond length is 1.94 Å. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one Ni(1)O5 trigonal bipyramid, and  an edgeedge with one Ni(1)O5 trigonal bipyramid. The P(1)-O(1) bond length is 1.53 Å. The P(1)-O(2) bond length is 1.53 Å. The P(1)-O(3) bond length is 1.68 Å. The P(1)-O(6) bond length is 1.52 Å. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Ni(1)O5 trigonal bipyramids. The P(2)-O(3) bond length is 1.65 Å. The P(2)-O(4) bond length is 1.55 Å. The P(2)-O(5) bond length is 1.52 Å. The P(2)-O(8) bond length is 1.51 Å. In the third P site, P(3) is bonded to one O(11), one O(13), one O(7), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one P(4)O4 tetrahedra and  a cornercorner with one Ni(1)O5 trigonal bipyramid. The P(3)-O(11) bond length is 1.52 Å. The P(3)-O(13) bond length is 1.54 Å. The P(3)-O(7) bond length is 1.51 Å. The P(3)-O(9) bond length is 1.66 Å. In the fourth P site, P(4) is bonded to one O(10), one O(12), one O(14), and one O(9) atom to form corner-sharing PO4 tetrahedra. The P(4)-O(10) bond length is 1.54 Å. The P(4)-O(12) bond length is 1.54 Å. The P(4)-O(14) bond length is 1.54 Å. The P(4)-O(9) bond length is 1.62 Å. There are fourteen 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 T-shaped geometry to one Li(1), one Ni(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ni(1), one P(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Li(1), one Ni(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(2) and one P(2) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Li(2), one Ni(2), and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(3) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Ni(3) and one P(2) atom. In the ninth O site, O(9) is bonded in a distorted bent 120 degrees geometry to one Ni(2), one P(3), and one P(4) atom. In the tenth O site, O(10) is bonded in a distorted water-like geometry to one Li(2), one Ni(2), and one P(4) atom. In the eleventh O site, O(11) is bonded in a bent 120 degrees geometry to one Ni(2) and one P(3) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Li(2), one Ni(3), and one P(4) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Li(2), one Ni(3), and one P(3) atom. In the fourteenth O site, O(14) is bonded in a distorted trigonal planar geometry to one Li(2), one Ni(3), and one P(4) atom.