CrP2O7 crystallizes in the monoclinic P2_1/c space group. Cr(1) is bonded to one O(3), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form CrO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Cr(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(4), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-56°. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 13-45°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a single-bond geometry to one P(1) atom. In the third O site, O(3) is bonded in a linear geometry to one Cr(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Cr(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Cr(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(1) atom.
CrP2O7 crystallizes in the monoclinic P2_1/c space group. Cr(1) is bonded to one O(3), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form CrO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Cr(1)O6 octahedra. The Cr(1)-O(3) bond length is 1.95 Å. The Cr(1)-O(5) bond length is 1.97 Å. The Cr(1)-O(6) bond length is 1.90 Å. The Cr(1)-O(7) bond length is 1.93 Å. There is one shorter (2.11 Å) and one longer (2.12 Å) Cr(1)-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(4), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-56°. The P(1)-O(1) bond length is 1.59 Å. The P(1)-O(2) bond length is 1.50 Å. The P(1)-O(4) bond length is 1.58 Å. The P(1)-O(7) bond length is 1.53 Å. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 13-45°. The P(2)-O(1) bond length is 1.61 Å. The P(2)-O(3) bond length is 1.52 Å. The P(2)-O(5) bond length is 1.52 Å. The P(2)-O(6) bond length is 1.53 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a single-bond geometry to one P(1) atom. In the third O site, O(3) is bonded in a linear geometry to one Cr(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Cr(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Cr(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(1) atom.