Co2P2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(2), one O(3), one O(6), and one O(7) atom to form CoO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Co(2)O6 octahedra. In the second Co site, Co(2) is bonded to one O(1), one O(2), one O(6), one O(7), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Co(2)O6 octahedra, and edges with two equivalent Co(1)O5 trigonal bipyramids. 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 Co(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with three equivalent Co(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 33-50°. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Co(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Co(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 46-52°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Co(1), one Co(2), and one P(1) atom. In the third O site, O(7) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(2), and one P(2) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Co(1), one Co(2), and one P(1) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(2), and one P(1) atom. In the sixth O site, O(3) is bonded in a bent 150 degrees geometry to one Co(1) and one P(2) atom. In the seventh O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Co(2) and one P(2) atom.
Co2P2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(2), one O(3), one O(6), and one O(7) atom to form CoO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Co(2)O6 octahedra. The Co(1)-O(1) bond length is 2.09 Å. The Co(1)-O(2) bond length is 2.05 Å. The Co(1)-O(3) bond length is 1.95 Å. The Co(1)-O(6) bond length is 2.06 Å. The Co(1)-O(7) bond length is 2.03 Å. In the second Co site, Co(2) is bonded to one O(1), one O(2), one O(6), one O(7), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Co(2)O6 octahedra, and edges with two equivalent Co(1)O5 trigonal bipyramids. The Co(2)-O(1) bond length is 2.15 Å. The Co(2)-O(2) bond length is 2.15 Å. The Co(2)-O(6) bond length is 2.09 Å. The Co(2)-O(7) bond length is 2.07 Å. There is one shorter (2.07 Å) and one longer (2.12 Å) Co(2)-O(4) 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 Co(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with three equivalent Co(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 33-50°. The P(1)-O(1) bond length is 1.53 Å. The P(1)-O(2) bond length is 1.52 Å. The P(1)-O(5) bond length is 1.58 Å. The P(1)-O(6) bond length is 1.53 Å. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Co(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Co(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 46-52°. The P(2)-O(3) bond length is 1.49 Å. The P(2)-O(4) bond length is 1.52 Å. The P(2)-O(5) bond length is 1.59 Å. The P(2)-O(7) bond length is 1.53 Å. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Co(1), one Co(2), and one P(1) atom. In the third O site, O(7) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(2), and one P(2) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Co(1), one Co(2), and one P(1) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(2), and one P(1) atom. In the sixth O site, O(3) is bonded in a bent 150 degrees geometry to one Co(1) and one P(2) atom. In the seventh O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Co(2) and one P(2) atom.