CaTiP2O7 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one O(6), and one O(7) atom. Ti(1) is bonded to one O(3), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form TiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Ti(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 Ti(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-53°. 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 Ti(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-45°. 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 bent 150 degrees geometry to one Ca(1) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Ti(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Ti(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ti(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ti(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ti(1), and one P(1) atom.
CaTiP2O7 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one O(6), and one O(7) atom. The Ca(1)-O(2) bond length is 2.27 Å. The Ca(1)-O(3) bond length is 2.42 Å. The Ca(1)-O(5) bond length is 2.32 Å. The Ca(1)-O(6) bond length is 2.35 Å. The Ca(1)-O(7) bond length is 2.33 Å. Ti(1) is bonded to one O(3), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form TiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Ti(1)O6 octahedra. The Ti(1)-O(3) bond length is 2.28 Å. The Ti(1)-O(5) bond length is 2.23 Å. The Ti(1)-O(6) bond length is 2.23 Å. The Ti(1)-O(7) bond length is 2.19 Å. There is one shorter (2.14 Å) and one longer (2.18 Å) Ti(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 Ti(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-53°. The P(1)-O(1) bond length is 1.62 Å. The P(1)-O(2) bond length is 1.51 Å. The P(1)-O(4) bond length is 1.55 Å. The P(1)-O(7) bond length is 1.54 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 Ti(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-45°. The P(2)-O(1) bond length is 1.62 Å. The P(2)-O(3) bond length is 1.53 Å. The P(2)-O(5) bond length is 1.54 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 150 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Ti(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Ti(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ti(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ti(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ti(1), and one P(1) atom.