TiNiP2O9 crystallizes in the orthorhombic Pnma space group. Ti(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), one O(6), one O(7), and two equivalent O(5) atoms. Ni(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(7), and two equivalent O(5) atoms to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. In the second P site, P(2) is bonded to one O(4), one O(6), and two equivalent O(1) atoms to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a water-like geometry to one Ti(1) and one P(2) atom. In the second O site, O(5) is bonded in a bent 150 degrees geometry to one Ti(1) and one P(1) atom. In the third O site, O(6) is bonded in a distorted L-shaped geometry to one Ti(1) and one P(2) atom. In the fourth O site, O(1) is bonded in a bent 120 degrees geometry to one Ni(1) and one P(2) atom. In the fifth O site, O(7) is bonded in a linear geometry to one Ti(1) and one P(1) atom. In the sixth O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one P(1) atom. In the seventh O site, O(3) is bonded in a distorted trigonal planar geometry to one Ti(1) and two equivalent Ni(1) atoms.
TiNiP2O9 crystallizes in the orthorhombic Pnma space group. Ti(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), one O(6), one O(7), and two equivalent O(5) atoms. The Ti(1)-O(3) bond length is 1.75 Å. The Ti(1)-O(4) bond length is 2.04 Å. The Ti(1)-O(6) bond length is 2.39 Å. The Ti(1)-O(7) bond length is 1.97 Å. Both Ti(1)-O(5) bond lengths are 1.96 Å. Ni(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. Both Ni(1)-O(1) bond lengths are 1.97 Å. Both Ni(1)-O(2) bond lengths are 2.08 Å. Both Ni(1)-O(3) bond lengths are 2.11 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(7), and two equivalent O(5) atoms to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. The P(1)-O(2) bond length is 1.55 Å. The P(1)-O(7) bond length is 1.54 Å. Both P(1)-O(5) bond lengths are 1.54 Å. In the second P site, P(2) is bonded to one O(4), one O(6), and two equivalent O(1) atoms to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. The P(2)-O(4) bond length is 1.56 Å. The P(2)-O(6) bond length is 1.56 Å. Both P(2)-O(1) bond lengths are 1.54 Å. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a water-like geometry to one Ti(1) and one P(2) atom. In the second O site, O(5) is bonded in a bent 150 degrees geometry to one Ti(1) and one P(1) atom. In the third O site, O(6) is bonded in a distorted L-shaped geometry to one Ti(1) and one P(2) atom. In the fourth O site, O(1) is bonded in a bent 120 degrees geometry to one Ni(1) and one P(2) atom. In the fifth O site, O(7) is bonded in a linear geometry to one Ti(1) and one P(1) atom. In the sixth O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one P(1) atom. In the seventh O site, O(3) is bonded in a distorted trigonal planar geometry to one Ti(1) and two equivalent Ni(1) atoms.