SnP2O7 crystallizes in the monoclinic P2_1/c space group. Sn(1) is bonded to one O(1), one O(3), one O(4), one O(5), and one O(6) atom to form SnO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)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(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with three equivalent Sn(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(2), one O(3), one O(4), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Sn(1)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Sn(1) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Sn(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Sn(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Sn(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Sn(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a single-bond geometry to one P(2) atom.
SnP2O7 crystallizes in the monoclinic P2_1/c space group. Sn(1) is bonded to one O(1), one O(3), one O(4), one O(5), and one O(6) atom to form SnO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. The Sn(1)-O(1) bond length is 2.00 Å. The Sn(1)-O(3) bond length is 2.02 Å. The Sn(1)-O(4) bond length is 2.00 Å. The Sn(1)-O(5) bond length is 2.03 Å. The Sn(1)-O(6) bond length is 2.07 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(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with three equivalent Sn(1)O5 trigonal bipyramids. The P(1)-O(1) bond length is 1.55 Å. The P(1)-O(2) bond length is 1.55 Å. The P(1)-O(5) bond length is 1.54 Å. The P(1)-O(6) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(2), one O(3), one O(4), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Sn(1)O5 trigonal bipyramids. The P(2)-O(2) bond length is 1.66 Å. The P(2)-O(3) bond length is 1.56 Å. The P(2)-O(4) bond length is 1.57 Å. The P(2)-O(7) bond length is 1.47 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Sn(1) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Sn(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Sn(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Sn(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Sn(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a single-bond geometry to one P(2) atom.