TaBi(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Ta(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(6) atoms to form TaO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with four equivalent P(1)O4 tetrahedra. Bi(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form BiO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with four equivalent P(2)O4 tetrahedra. 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  a cornercorner with one Bi(1)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 11-22°. In the second P site, P(2) is bonded to one O(2), one O(3), one O(6), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Bi(1)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-34°. There are eight inequivalent O sites. In the first O site, O(7) is bonded in a linear geometry to two equivalent P(1) atoms. In the second O site, O(8) is bonded in a linear geometry to two equivalent P(2) atoms. In the third O site, O(1) is bonded in a linear geometry to one Ta(1) and one P(1) atom. In the fourth O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Bi(1) and one P(2) atom. In the fifth O site, O(3) is bonded in a bent 150 degrees geometry to one Bi(1) and one P(2) atom. In the sixth O site, O(4) is bonded in a linear geometry to one Ta(1) and one P(1) atom. In the seventh O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Bi(1) and one P(1) atom. In the eighth O site, O(6) is bonded in a bent 150 degrees geometry to one Ta(1) and one P(2) atom.
TaBi(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Ta(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(6) atoms to form TaO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with four equivalent P(1)O4 tetrahedra. Both Ta(1)-O(1) bond lengths are 1.97 Å. Both Ta(1)-O(4) bond lengths are 1.97 Å. Both Ta(1)-O(6) bond lengths are 1.93 Å. Bi(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form BiO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with four equivalent P(2)O4 tetrahedra. Both Bi(1)-O(2) bond lengths are 2.31 Å. Both Bi(1)-O(3) bond lengths are 2.31 Å. Both Bi(1)-O(5) bond lengths are 2.36 Å. 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  a cornercorner with one Bi(1)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 11-22°. The P(1)-O(1) bond length is 1.52 Å. The P(1)-O(4) bond length is 1.53 Å. The P(1)-O(5) bond length is 1.48 Å. The P(1)-O(7) bond length is 1.57 Å. In the second P site, P(2) is bonded to one O(2), one O(3), one O(6), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Bi(1)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-34°. The P(2)-O(2) bond length is 1.49 Å. The P(2)-O(3) bond length is 1.49 Å. The P(2)-O(6) bond length is 1.55 Å. The P(2)-O(8) bond length is 1.56 Å. There are eight inequivalent O sites. In the first O site, O(7) is bonded in a linear geometry to two equivalent P(1) atoms. In the second O site, O(8) is bonded in a linear geometry to two equivalent P(2) atoms. In the third O site, O(1) is bonded in a linear geometry to one Ta(1) and one P(1) atom. In the fourth O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Bi(1) and one P(2) atom. In the fifth O site, O(3) is bonded in a bent 150 degrees geometry to one Bi(1) and one P(2) atom. In the sixth O site, O(4) is bonded in a linear geometry to one Ta(1) and one P(1) atom. In the seventh O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Bi(1) and one P(1) atom. In the eighth O site, O(6) is bonded in a bent 150 degrees geometry to one Ta(1) and one P(2) atom.