K2CdP2O7 crystallizes in the monoclinic C2/c space group. K(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(4), three equivalent O(2), and three equivalent O(3) atoms. Cd(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CdO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Cd(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 22-48°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1) and two equivalent P(1) atoms. In the second O site, O(2) is bonded in a 1-coordinate geometry to three equivalent K(1), one Cd(1), and one P(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to three equivalent K(1), one Cd(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to two equivalent K(1), one Cd(1), and one P(1) atom.
K2CdP2O7 crystallizes in the monoclinic C2/c space group. K(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(4), three equivalent O(2), and three equivalent O(3) atoms. The K(1)-O(1) bond length is 2.91 Å. There is one shorter (2.89 Å) and one longer (3.11 Å) K(1)-O(4) bond length. There are a spread of K(1)-O(2) bond distances ranging from 2.72-3.05 Å. There are a spread of K(1)-O(3) bond distances ranging from 2.88-3.13 Å. Cd(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CdO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. Both Cd(1)-O(2) bond lengths are 2.32 Å. Both Cd(1)-O(3) bond lengths are 2.33 Å. Both Cd(1)-O(4) bond lengths are 2.37 Å. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Cd(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 22-48°. The P(1)-O(1) bond length is 1.66 Å. The P(1)-O(2) bond length is 1.54 Å. The P(1)-O(3) bond length is 1.54 Å. The P(1)-O(4) bond length is 1.52 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1) and two equivalent P(1) atoms. In the second O site, O(2) is bonded in a 1-coordinate geometry to three equivalent K(1), one Cd(1), and one P(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to three equivalent K(1), one Cd(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to two equivalent K(1), one Cd(1), and one P(1) atom.