CsLuP2O7 crystallizes in the monoclinic P2_1/c space group. Cs(1) is bonded in a 10-coordinate geometry to one O(1), one O(4), one O(5), one O(7), two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms. Lu(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form LuO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Lu(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 13-45°. In the second P site, P(2) is bonded to one O(1), one O(2), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Lu(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 13-47°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Cs(1), one Lu(1), and one P(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Cs(1), one Lu(1), and one P(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Cs(1), one Lu(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to one Cs(1), one Lu(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Cs(1), one Lu(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to two equivalent Cs(1), one Lu(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one Cs(1), one P(1), and one P(2) atom.
CsLuP2O7 crystallizes in the monoclinic P2_1/c space group. Cs(1) is bonded in a 10-coordinate geometry to one O(1), one O(4), one O(5), one O(7), two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms. The Cs(1)-O(1) bond length is 3.43 Å. The Cs(1)-O(4) bond length is 3.64 Å. The Cs(1)-O(5) bond length is 3.10 Å. The Cs(1)-O(7) bond length is 3.43 Å. There is one shorter (3.32 Å) and one longer (3.49 Å) Cs(1)-O(2) bond length. Both Cs(1)-O(3) bond lengths are 3.30 Å. There is one shorter (3.12 Å) and one longer (3.23 Å) Cs(1)-O(6) bond length. Lu(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form LuO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. The Lu(1)-O(1) bond length is 2.20 Å. The Lu(1)-O(2) bond length is 2.19 Å. The Lu(1)-O(3) bond length is 2.21 Å. The Lu(1)-O(4) bond length is 2.16 Å. The Lu(1)-O(5) bond length is 2.20 Å. The Lu(1)-O(6) bond length is 2.23 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Lu(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 13-45°. The P(1)-O(3) bond length is 1.54 Å. The P(1)-O(4) bond length is 1.52 Å. The P(1)-O(6) bond length is 1.54 Å. The P(1)-O(7) bond length is 1.63 Å. In the second P site, P(2) is bonded to one O(1), one O(2), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Lu(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 13-47°. The P(2)-O(1) bond length is 1.53 Å. The P(2)-O(2) bond length is 1.53 Å. The P(2)-O(5) bond length is 1.53 Å. The P(2)-O(7) bond length is 1.64 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Cs(1), one Lu(1), and one P(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Cs(1), one Lu(1), and one P(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Cs(1), one Lu(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to one Cs(1), one Lu(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Cs(1), one Lu(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to two equivalent Cs(1), one Lu(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one Cs(1), one P(1), and one P(2) atom.