Ni7(PO4)6 crystallizes in the monoclinic C2/m space group. 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 two equivalent O(5) atoms to form NiO6 octahedra that share  a cornercorner with one Ni(3)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra,  an edgeedge with one Ni(1)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-61°. In the second Ni site, Ni(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra,  an edgeedge with one Ni(2)O6 octahedra, and edges with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-61°. In the third Ni site, Ni(3) is bonded to two equivalent O(6) and four equivalent O(2) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with four equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. There are two 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(5) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra, corners with three equivalent Ni(1)O6 octahedra, and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-59°. In the second P site, P(2) is bonded to one O(6), one O(7), and two equivalent O(4) atoms to form PO4 tetrahedra that share  a cornercorner with one Ni(3)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-55°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one P(1) atom. In the second O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Ni(3) and one P(2) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Ni(2) and one P(2) atom. In the fourth O site, O(1) is bonded in a bent 150 degrees geometry to one Ni(1) and one P(1) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(3), and one P(1) atom. In the sixth O site, O(3) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(1) atom. In the seventh O site, O(4) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(2) atom.
Ni7(PO4)6 crystallizes in the monoclinic C2/m space group. 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 two equivalent O(5) atoms to form NiO6 octahedra that share  a cornercorner with one Ni(3)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra,  an edgeedge with one Ni(1)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-61°. The Ni(1)-O(1) bond length is 2.01 Å. The Ni(1)-O(2) bond length is 2.07 Å. The Ni(1)-O(3) bond length is 2.10 Å. The Ni(1)-O(4) bond length is 2.02 Å. There is one shorter (2.05 Å) and one longer (2.08 Å) Ni(1)-O(5) bond length. In the second Ni site, Ni(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra,  an edgeedge with one Ni(2)O6 octahedra, and edges with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-61°. Both Ni(2)-O(3) bond lengths are 2.07 Å. Both Ni(2)-O(4) bond lengths are 2.05 Å. Both Ni(2)-O(7) bond lengths are 2.15 Å. In the third Ni site, Ni(3) is bonded to two equivalent O(6) and four equivalent O(2) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with four equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. Both Ni(3)-O(6) bond lengths are 1.99 Å. All Ni(3)-O(2) bond lengths are 2.09 Å. There are two 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(5) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra, corners with three equivalent Ni(1)O6 octahedra, and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-59°. The P(1)-O(1) bond length is 1.52 Å. The P(1)-O(2) bond length is 1.58 Å. The P(1)-O(3) bond length is 1.58 Å. The P(1)-O(5) bond length is 1.55 Å. In the second P site, P(2) is bonded to one O(6), one O(7), and two equivalent O(4) atoms to form PO4 tetrahedra that share  a cornercorner with one Ni(3)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-55°. The P(2)-O(6) bond length is 1.51 Å. The P(2)-O(7) bond length is 1.57 Å. Both P(2)-O(4) bond lengths are 1.57 Å. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one P(1) atom. In the second O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Ni(3) and one P(2) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Ni(2) and one P(2) atom. In the fourth O site, O(1) is bonded in a bent 150 degrees geometry to one Ni(1) and one P(1) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(3), and one P(1) atom. In the sixth O site, O(3) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(1) atom. In the seventh O site, O(4) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(2) atom.