K2CSbPO7 crystallizes in the monoclinic P2_1/m space group. K(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 distorted KO6 octahedra that share  a cornercorner with one Sb(1)O5 square pyramid, corners with three equivalent P(1)O4 tetrahedra,  an edgeedge with one K(1)O6 octahedra,  a faceface with one K(1)O6 octahedra, and  a faceface with one Sb(1)O5 square pyramid. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. Sb(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted SbO5 square pyramids that share corners with two equivalent K(1)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and faces with two equivalent K(1)O6 octahedra. The corner-sharing octahedral tilt angles are 77°. P(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with six equivalent K(1)O6 octahedra and corners with three equivalent Sb(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 48-59°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent K(1) and one C(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent K(1), one C(1), and one Sb(1) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one C(1), and one Sb(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one K(1), one Sb(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent K(1), one Sb(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent K(1) and one P(1) atom.
K2CSbPO7 crystallizes in the monoclinic P2_1/m space group. K(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 distorted KO6 octahedra that share  a cornercorner with one Sb(1)O5 square pyramid, corners with three equivalent P(1)O4 tetrahedra,  an edgeedge with one K(1)O6 octahedra,  a faceface with one K(1)O6 octahedra, and  a faceface with one Sb(1)O5 square pyramid. The K(1)-O(1) bond length is 2.66 Å. The K(1)-O(2) bond length is 2.72 Å. The K(1)-O(3) bond length is 2.66 Å. The K(1)-O(4) bond length is 2.90 Å. The K(1)-O(5) bond length is 2.87 Å. The K(1)-O(6) bond length is 2.71 Å. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. The C(1)-O(1) bond length is 1.25 Å. The C(1)-O(2) bond length is 1.36 Å. The C(1)-O(3) bond length is 1.30 Å. Sb(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted SbO5 square pyramids that share corners with two equivalent K(1)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and faces with two equivalent K(1)O6 octahedra. The corner-sharing octahedral tilt angles are 77°. The Sb(1)-O(2) bond length is 2.08 Å. The Sb(1)-O(3) bond length is 2.45 Å. The Sb(1)-O(5) bond length is 2.12 Å. Both Sb(1)-O(4) bond lengths are 2.29 Å. P(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with six equivalent K(1)O6 octahedra and corners with three equivalent Sb(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 48-59°. The P(1)-O(5) bond length is 1.61 Å. The P(1)-O(6) bond length is 1.52 Å. Both P(1)-O(4) bond lengths are 1.57 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent K(1) and one C(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent K(1), one C(1), and one Sb(1) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one C(1), and one Sb(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one K(1), one Sb(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent K(1), one Sb(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent K(1) and one P(1) atom.