Sn2P2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 6-coordinate geometry to one O(1), one O(4), one O(6), one O(7), and two equivalent O(2) atoms. In the second Sn site, Sn(2) is bonded to one O(1), one O(4), one O(6), and two equivalent O(5) atoms to form distorted SnO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Sn(2)O5 trigonal bipyramid. 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(5) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with three equivalent Sn(2)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(3), one O(4), one O(6), 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(2)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Sn(1), one Sn(2), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Sn(1) and one P(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one Sn(1), one Sn(2), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Sn(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Sn(1), one Sn(2), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Sn(1) and one P(2) atom.
Sn2P2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 6-coordinate geometry to one O(1), one O(4), one O(6), one O(7), and two equivalent O(2) atoms. The Sn(1)-O(1) bond length is 2.58 Å. The Sn(1)-O(4) bond length is 2.71 Å. The Sn(1)-O(6) bond length is 2.51 Å. The Sn(1)-O(7) bond length is 2.30 Å. There is one shorter (2.52 Å) and one longer (2.58 Å) Sn(1)-O(2) bond length. In the second Sn site, Sn(2) is bonded to one O(1), one O(4), one O(6), and two equivalent O(5) atoms to form distorted SnO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Sn(2)O5 trigonal bipyramid. The Sn(2)-O(1) bond length is 2.56 Å. The Sn(2)-O(4) bond length is 2.33 Å. The Sn(2)-O(6) bond length is 2.55 Å. There is one shorter (2.39 Å) and one longer (2.75 Å) Sn(2)-O(5) bond length. 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(5) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with three equivalent Sn(2)O5 trigonal bipyramids. The P(1)-O(1) bond length is 1.54 Å. The P(1)-O(2) bond length is 1.56 Å. The P(1)-O(3) bond length is 1.63 Å. The P(1)-O(5) bond length is 1.53 Å. In the second P site, P(2) is bonded to one O(3), one O(4), one O(6), 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(2)O5 trigonal bipyramids. The P(2)-O(3) bond length is 1.64 Å. The P(2)-O(4) 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 1.53 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Sn(1), one Sn(2), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Sn(1) and one P(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one Sn(1), one Sn(2), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Sn(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Sn(1), one Sn(2), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Sn(1) and one P(2) atom.