SbP2O7 crystallizes in the monoclinic P2_1 space group. Sb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form SbO6 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(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Sb(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-48°. In the second P site, P(2) is bonded to one O(1), one O(2), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Sb(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-49°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Sb(1) and one P(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Sb(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Sb(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Sb(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Sb(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Sb(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom.
SbP2O7 crystallizes in the monoclinic P2_1 space group. Sb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form SbO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. The Sb(1)-O(1) bond length is 2.14 Å. The Sb(1)-O(2) bond length is 2.13 Å. The Sb(1)-O(3) bond length is 2.14 Å. The Sb(1)-O(4) bond length is 2.12 Å. The Sb(1)-O(5) bond length is 2.13 Å. The Sb(1)-O(6) bond length is 2.16 Å. There are two inequivalent P sites. In the first P site, P(1) 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 Sb(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-48°. The P(1)-O(3) bond length is 1.53 Å. The P(1)-O(4) bond length is 1.54 Å. The P(1)-O(5) bond length is 1.54 Å. The P(1)-O(7) bond length is 1.61 Å. In the second P site, P(2) is bonded to one O(1), one O(2), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Sb(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-49°. The P(2)-O(1) bond length is 1.54 Å. The P(2)-O(2) bond length is 1.53 Å. The P(2)-O(6) bond length is 1.54 Å. The P(2)-O(7) bond length is 1.62 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Sb(1) and one P(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Sb(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Sb(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Sb(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Sb(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Sb(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom.