BiP2O7 crystallizes in the triclinic P-1 space group. Bi(1) is bonded to one O(1), one O(3), one O(5), one O(7), and two equivalent O(6) atoms to form BiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Bi(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Bi(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-47°. In the second P site, P(2) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Bi(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-58°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Bi(1) and one P(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one P(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Bi(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Bi(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Bi(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Bi(1) and one P(1) atom.
BiP2O7 crystallizes in the triclinic P-1 space group. Bi(1) is bonded to one O(1), one O(3), one O(5), one O(7), and two equivalent O(6) atoms to form BiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Bi(1)O6 octahedra. The Bi(1)-O(1) bond length is 2.32 Å. The Bi(1)-O(3) bond length is 2.31 Å. The Bi(1)-O(5) bond length is 2.27 Å. The Bi(1)-O(7) bond length is 2.23 Å. There is one shorter (2.41 Å) and one longer (2.52 Å) Bi(1)-O(6) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Bi(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-47°. The P(1)-O(1) bond length is 1.52 Å. The P(1)-O(4) bond length is 1.62 Å. The P(1)-O(5) bond length is 1.53 Å. The P(1)-O(7) bond length is 1.55 Å. In the second P site, P(2) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Bi(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-58°. The P(2)-O(2) bond length is 1.51 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(6) bond length is 1.56 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Bi(1) and one P(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one P(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Bi(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Bi(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Bi(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Bi(1) and one P(1) atom.