WP2O7 crystallizes in the monoclinic P2_1/c space group. W(1) is bonded to one O(1), one O(3), one O(4), one O(5), and one O(6) atom to form WO5 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 W(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 W(1)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one W(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 150 degrees geometry to one W(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one W(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one W(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one W(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.
WP2O7 crystallizes in the monoclinic P2_1/c space group. W(1) is bonded to one O(1), one O(3), one O(4), one O(5), and one O(6) atom to form WO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. The W(1)-O(1) bond length is 1.98 Å. The W(1)-O(3) bond length is 2.06 Å. The W(1)-O(4) bond length is 1.97 Å. The W(1)-O(5) bond length is 2.00 Å. The W(1)-O(6) bond length is 2.13 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 W(1)O5 trigonal bipyramids. The P(1)-O(1) bond length is 1.56 Å. The P(1)-O(2) bond length is 1.56 Å. The P(1)-O(5) bond length is 1.55 Å. The P(1)-O(6) bond length is 1.52 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 W(1)O5 trigonal bipyramids. The P(2)-O(2) bond length is 1.65 Å. The P(2)-O(3) bond length is 1.54 Å. The P(2)-O(4) bond length is 1.59 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 distorted bent 120 degrees geometry to one W(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 150 degrees geometry to one W(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one W(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one W(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one W(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.