In2P2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent In sites. In the first In site, In(1) is bonded in a 1-coordinate geometry to one O(7) atom. In the second In site, In(2) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form InO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. 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(6) atom to form PO4 tetrahedra that share corners with three equivalent In(2)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-54°. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent In(2)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-50°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a bent 150 degrees geometry to one In(2) and one P(2) atom. In the second O site, O(6) is bonded in a distorted bent 120 degrees geometry to one In(2) and one P(1) atom. In the third O site, O(7) is bonded in a 2-coordinate geometry to one In(1), one In(2), and one P(2) atom. In the fourth O site, O(1) is bonded in a bent 150 degrees geometry to one In(2) and one P(1) atom. In the fifth O site, O(2) is bonded in a bent 150 degrees geometry to one In(2) and one P(1) atom. In the sixth O site, O(3) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the seventh O site, O(4) is bonded in a 2-coordinate geometry to one In(2) and one P(2) atom.
In2P2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent In sites. In the first In site, In(1) is bonded in a 1-coordinate geometry to one O(7) atom. The In(1)-O(7) bond length is 2.74 Å. In the second In site, In(2) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form InO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. The In(2)-O(1) bond length is 2.14 Å. The In(2)-O(2) bond length is 2.11 Å. The In(2)-O(4) bond length is 2.18 Å. The In(2)-O(5) bond length is 2.11 Å. The In(2)-O(6) bond length is 2.14 Å. The In(2)-O(7) bond length is 2.17 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(6) atom to form PO4 tetrahedra that share corners with three equivalent In(2)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-54°. The P(1)-O(1) bond length is 1.51 Å. The P(1)-O(2) bond length is 1.51 Å. The P(1)-O(3) bond length is 1.62 Å. The P(1)-O(6) bond length is 1.52 Å. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent In(2)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-50°. The P(2)-O(3) bond length is 1.60 Å. The P(2)-O(4) bond length is 1.53 Å. The P(2)-O(5) bond length is 1.49 Å. The P(2)-O(7) bond length is 1.53 Å. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a bent 150 degrees geometry to one In(2) and one P(2) atom. In the second O site, O(6) is bonded in a distorted bent 120 degrees geometry to one In(2) and one P(1) atom. In the third O site, O(7) is bonded in a 2-coordinate geometry to one In(1), one In(2), and one P(2) atom. In the fourth O site, O(1) is bonded in a bent 150 degrees geometry to one In(2) and one P(1) atom. In the fifth O site, O(2) is bonded in a bent 150 degrees geometry to one In(2) and one P(1) atom. In the sixth O site, O(3) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the seventh O site, O(4) is bonded in a 2-coordinate geometry to one In(2) and one P(2) atom.