Ti2P2O11 crystallizes in the triclinic P-1 space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(10), one O(11), one O(3), one O(7), one O(8), and one O(9) atom to form distorted TiO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. In the second Ti site, Ti(2) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(9) atom to form TiO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with three equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. There are two inequivalent P sites. In the first P site, 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  a cornercorner with one Ti(1)O6 octahedra and corners with three equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 15-30°. In the second P site, P(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-43°. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Ti(2) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Ti(2) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ti(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ti(2) and one P(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Ti(2) and one P(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Ti(2) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Ti(1) and one P(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Ti(1) and one P(2) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Ti(1) and one Ti(2) atom. In the tenth O site, O(10) is bonded in a single-bond geometry to one Ti(1) atom. In the eleventh O site, O(11) is bonded in a single-bond geometry to one Ti(1) atom.
Ti2P2O11 crystallizes in the triclinic P-1 space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(10), one O(11), one O(3), one O(7), one O(8), and one O(9) atom to form distorted TiO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. The Ti(1)-O(10) bond length is 1.95 Å. The Ti(1)-O(11) bond length is 2.11 Å. The Ti(1)-O(3) bond length is 1.94 Å. The Ti(1)-O(7) bond length is 1.98 Å. The Ti(1)-O(8) bond length is 1.95 Å. The Ti(1)-O(9) bond length is 1.82 Å. In the second Ti site, Ti(2) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(9) atom to form TiO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with three equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. The Ti(2)-O(1) bond length is 2.03 Å. The Ti(2)-O(2) bond length is 1.99 Å. The Ti(2)-O(4) bond length is 1.96 Å. The Ti(2)-O(5) bond length is 1.96 Å. The Ti(2)-O(6) bond length is 1.98 Å. The Ti(2)-O(9) bond length is 1.83 Å. There are two inequivalent P sites. In the first P site, 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  a cornercorner with one Ti(1)O6 octahedra and corners with three equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 15-30°. The P(1)-O(1) bond length is 1.53 Å. The P(1)-O(2) bond length is 1.55 Å. The P(1)-O(3) bond length is 1.56 Å. The P(1)-O(4) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-43°. The P(2)-O(5) bond length is 1.54 Å. The P(2)-O(6) bond length is 1.54 Å. The P(2)-O(7) bond length is 1.56 Å. The P(2)-O(8) bond length is 1.55 Å. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Ti(2) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Ti(2) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ti(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ti(2) and one P(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Ti(2) and one P(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Ti(2) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Ti(1) and one P(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Ti(1) and one P(2) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Ti(1) and one Ti(2) atom. In the tenth O site, O(10) is bonded in a single-bond geometry to one Ti(1) atom. In the eleventh O site, O(11) is bonded in a single-bond geometry to one Ti(1) atom.