CaNiP2O7 crystallizes in the triclinic P-1 space group. Ca(1) is bonded in a 7-coordinate geometry to one O(2), one O(3), one O(4), one O(6), one O(7), and two equivalent O(5) atoms. Ni(1) is bonded to one O(2), one O(3), one O(4), one O(7), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Ni(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), 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 44-60°. In the second P site, P(2) is bonded to one O(1), 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 42-55°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ni(1), and one P(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ca(1), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Ni(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Ca(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Ni(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ni(1), and one P(2) atom.
CaNiP2O7 crystallizes in the triclinic P-1 space group. Ca(1) is bonded in a 7-coordinate geometry to one O(2), one O(3), one O(4), one O(6), one O(7), and two equivalent O(5) atoms. The Ca(1)-O(2) bond length is 2.38 Å. The Ca(1)-O(3) bond length is 2.40 Å. The Ca(1)-O(4) bond length is 2.54 Å. The Ca(1)-O(6) bond length is 2.67 Å. The Ca(1)-O(7) bond length is 2.71 Å. There is one shorter (2.29 Å) and one longer (2.35 Å) Ca(1)-O(5) bond length. Ni(1) is bonded to one O(2), one O(3), one O(4), one O(7), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Ni(1)O6 octahedra. The Ni(1)-O(2) bond length is 2.12 Å. The Ni(1)-O(3) bond length is 2.10 Å. The Ni(1)-O(4) bond length is 2.16 Å. The Ni(1)-O(7) bond length is 2.09 Å. There is one shorter (2.14 Å) and one longer (2.19 Å) Ni(1)-O(6) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), 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 44-60°. The P(1)-O(1) bond length is 1.59 Å. The P(1)-O(2) bond length is 1.54 Å. The P(1)-O(5) bond length is 1.51 Å. The P(1)-O(6) bond length is 1.56 Å. In the second P site, P(2) is bonded to one O(1), 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 42-55°. The P(2)-O(1) bond length is 1.62 Å. The P(2)-O(3) bond length is 1.54 Å. The P(2)-O(4) bond length is 1.54 Å. The P(2)-O(7) bond length is 1.52 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ni(1), and one P(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ca(1), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Ni(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Ca(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Ni(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ni(1), and one P(2) atom.