Ni3(P2O7)2 crystallizes in the triclinic P-1 space group. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with two equivalent Ni(2)O5 trigonal bipyramids, and edges with two equivalent P(3)O4 tetrahedra. In the second Ni site, Ni(2) is bonded to one O(10), one O(13), one O(2), one O(7), and one O(8) atom to form NiO5 trigonal bipyramids that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with two equivalent P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 60-67°. In the third Ni site, Ni(3) is bonded to one O(1), one O(12), one O(13), one O(9), and two equivalent O(11) atoms to form NiO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra,  a cornercorner with one Ni(2)O5 trigonal bipyramid,  an edgeedge with one Ni(3)O6 octahedra, and  an edgeedge with one Ni(4)O6 octahedra. In the fourth Ni site, Ni(4) is bonded to two equivalent O(12), two equivalent O(5), and two equivalent O(9) atoms to form NiO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and edges with two equivalent Ni(3)O6 octahedra. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(11), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(4)O6 octahedra, corners with three equivalent Ni(3)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-58°. In the second P site, P(2) is bonded to one O(13), one O(2), one O(4), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Ni(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 54-67°. In the third P site, P(3) is bonded to one O(14), one O(3), one O(7), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(3)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one Ni(2)O5 trigonal bipyramid, and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-61°. In the fourth P site, P(4) is bonded to one O(10), one O(12), one O(14), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(3)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra, and corners with two equivalent Ni(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 56°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ni(3) and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Ni(2) and one P(2) atom. In the third O site, O(3) is bonded in an L-shaped geometry to one Ni(1) and one P(3) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Ni(4) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Ni(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ni(1), one Ni(2), and one P(3) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Ni(2) and one P(4) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Ni(3), one Ni(4), and one P(3) atom. In the tenth O site, O(10) is bonded in a bent 120 degrees geometry to one Ni(2) and one P(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to two equivalent Ni(3) and one P(1) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Ni(3), one Ni(4), and one P(4) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Ni(2), one Ni(3), and one P(2) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 120 degrees geometry to one P(3) and one P(4) atom.
Ni3(P2O7)2 crystallizes in the triclinic P-1 space group. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with two equivalent Ni(2)O5 trigonal bipyramids, and edges with two equivalent P(3)O4 tetrahedra. Both Ni(1)-O(3) bond lengths are 1.99 Å. Both Ni(1)-O(6) bond lengths are 2.00 Å. Both Ni(1)-O(7) bond lengths are 2.20 Å. In the second Ni site, Ni(2) is bonded to one O(10), one O(13), one O(2), one O(7), and one O(8) atom to form NiO5 trigonal bipyramids that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with two equivalent P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 60-67°. The Ni(2)-O(10) bond length is 1.98 Å. The Ni(2)-O(13) bond length is 2.15 Å. The Ni(2)-O(2) bond length is 2.01 Å. The Ni(2)-O(7) bond length is 2.00 Å. The Ni(2)-O(8) bond length is 2.02 Å. In the third Ni site, Ni(3) is bonded to one O(1), one O(12), one O(13), one O(9), and two equivalent O(11) atoms to form NiO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra,  a cornercorner with one Ni(2)O5 trigonal bipyramid,  an edgeedge with one Ni(3)O6 octahedra, and  an edgeedge with one Ni(4)O6 octahedra. The Ni(3)-O(1) bond length is 1.98 Å. The Ni(3)-O(12) bond length is 2.04 Å. The Ni(3)-O(13) bond length is 2.20 Å. The Ni(3)-O(9) bond length is 2.27 Å. There is one shorter (2.08 Å) and one longer (2.13 Å) Ni(3)-O(11) bond length. In the fourth Ni site, Ni(4) is bonded to two equivalent O(12), two equivalent O(5), and two equivalent O(9) atoms to form NiO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and edges with two equivalent Ni(3)O6 octahedra. Both Ni(4)-O(12) bond lengths are 2.07 Å. Both Ni(4)-O(5) bond lengths are 1.98 Å. Both Ni(4)-O(9) bond lengths are 2.17 Å. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(11), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(4)O6 octahedra, corners with three equivalent Ni(3)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-58°. The P(1)-O(1) bond length is 1.51 Å. The P(1)-O(11) bond length is 1.56 Å. The P(1)-O(4) bond length is 1.61 Å. The P(1)-O(5) bond length is 1.51 Å. In the second P site, P(2) is bonded to one O(13), one O(2), one O(4), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Ni(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 54-67°. The P(2)-O(13) bond length is 1.54 Å. The P(2)-O(2) bond length is 1.53 Å. The P(2)-O(4) bond length is 1.60 Å. The P(2)-O(6) bond length is 1.53 Å. In the third P site, P(3) is bonded to one O(14), one O(3), one O(7), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(3)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one Ni(2)O5 trigonal bipyramid, and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-61°. The P(3)-O(14) bond length is 1.61 Å. The P(3)-O(3) bond length is 1.55 Å. The P(3)-O(7) bond length is 1.54 Å. The P(3)-O(9) bond length is 1.53 Å. In the fourth P site, P(4) is bonded to one O(10), one O(12), one O(14), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(3)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra, and corners with two equivalent Ni(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 56°. The P(4)-O(10) bond length is 1.53 Å. The P(4)-O(12) bond length is 1.55 Å. The P(4)-O(14) bond length is 1.60 Å. The P(4)-O(8) bond length is 1.51 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ni(3) and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Ni(2) and one P(2) atom. In the third O site, O(3) is bonded in an L-shaped geometry to one Ni(1) and one P(3) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Ni(4) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Ni(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ni(1), one Ni(2), and one P(3) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Ni(2) and one P(4) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Ni(3), one Ni(4), and one P(3) atom. In the tenth O site, O(10) is bonded in a bent 120 degrees geometry to one Ni(2) and one P(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to two equivalent Ni(3) and one P(1) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Ni(3), one Ni(4), and one P(4) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Ni(2), one Ni(3), and one P(2) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 120 degrees geometry to one P(3) and one P(4) atom.