K2SbCl5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 9-coordinate geometry to one Cl(5), two equivalent Cl(1), two equivalent Cl(2), two equivalent Cl(3), and two equivalent Cl(4) atoms. In the second K site, K(2) is bonded to one Cl(1), one Cl(2), one Cl(4), two equivalent Cl(3), and two equivalent Cl(5) atoms to form distorted KCl7 pentagonal bipyramids that share corners with two equivalent K(2)Cl7 pentagonal bipyramids, corners with three equivalent Sb(1)Cl5 square pyramids,  an edgeedge with one K(2)Cl7 pentagonal bipyramid, and edges with two equivalent Sb(1)Cl5 square pyramids. Sb(1) is bonded to one Cl(1), one Cl(2), one Cl(3), one Cl(4), and one Cl(5) atom to form SbCl5 square pyramids that share corners with three equivalent K(2)Cl7 pentagonal bipyramids and edges with two equivalent K(2)Cl7 pentagonal bipyramids. There are five inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a distorted rectangular see-saw-like geometry to one K(2), two equivalent K(1), and one Sb(1) atom. In the second Cl site, Cl(2) is bonded to one K(2), two equivalent K(1), and one Sb(1) atom to form distorted ClK3Sb tetrahedra that share corners with five equivalent Cl(3)K4Sb square pyramids, corners with five equivalent Cl(5)K3Sb tetrahedra,  an edgeedge with one Cl(3)K4Sb square pyramid, and  an edgeedge with one Cl(2)K3Sb tetrahedra. In the third Cl site, Cl(3) is bonded to two equivalent K(1), two equivalent K(2), and one Sb(1) atom to form ClK4Sb square pyramids that share corners with two equivalent Cl(3)K4Sb square pyramids,  a cornercorner with one Cl(5)K3Sb tetrahedra, corners with five equivalent Cl(2)K3Sb tetrahedra,  an edgeedge with one Cl(3)K4Sb square pyramid,  an edgeedge with one Cl(2)K3Sb tetrahedra, and edges with three equivalent Cl(5)K3Sb tetrahedra. In the fourth Cl site, Cl(4) is bonded in a rectangular see-saw-like geometry to one K(2), two equivalent K(1), and one Sb(1) atom. In the fifth Cl site, Cl(5) is bonded to one K(1), two equivalent K(2), and one Sb(1) atom to form distorted ClK3Sb tetrahedra that share  a cornercorner with one Cl(3)K4Sb square pyramid, corners with two equivalent Cl(5)K3Sb tetrahedra, corners with five equivalent Cl(2)K3Sb tetrahedra, and edges with three equivalent Cl(3)K4Sb square pyramids.
K2SbCl5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 9-coordinate geometry to one Cl(5), two equivalent Cl(1), two equivalent Cl(2), two equivalent Cl(3), and two equivalent Cl(4) atoms. The K(1)-Cl(5) bond length is 3.41 Å. There is one shorter (3.28 Å) and one longer (3.60 Å) K(1)-Cl(1) bond length. There is one shorter (3.27 Å) and one longer (3.28 Å) K(1)-Cl(2) bond length. There is one shorter (3.22 Å) and one longer (3.27 Å) K(1)-Cl(3) bond length. There is one shorter (3.14 Å) and one longer (3.28 Å) K(1)-Cl(4) bond length. In the second K site, K(2) is bonded to one Cl(1), one Cl(2), one Cl(4), two equivalent Cl(3), and two equivalent Cl(5) atoms to form distorted KCl7 pentagonal bipyramids that share corners with two equivalent K(2)Cl7 pentagonal bipyramids, corners with three equivalent Sb(1)Cl5 square pyramids,  an edgeedge with one K(2)Cl7 pentagonal bipyramid, and edges with two equivalent Sb(1)Cl5 square pyramids. The K(2)-Cl(1) bond length is 3.21 Å. The K(2)-Cl(2) bond length is 3.30 Å. The K(2)-Cl(4) bond length is 3.15 Å. There is one shorter (3.28 Å) and one longer (3.31 Å) K(2)-Cl(3) bond length. There is one shorter (3.17 Å) and one longer (3.20 Å) K(2)-Cl(5) bond length. Sb(1) is bonded to one Cl(1), one Cl(2), one Cl(3), one Cl(4), and one Cl(5) atom to form SbCl5 square pyramids that share corners with three equivalent K(2)Cl7 pentagonal bipyramids and edges with two equivalent K(2)Cl7 pentagonal bipyramids. The Sb(1)-Cl(1) bond length is 2.41 Å. The Sb(1)-Cl(2) bond length is 2.54 Å. The Sb(1)-Cl(3) bond length is 2.76 Å. The Sb(1)-Cl(4) bond length is 2.64 Å. The Sb(1)-Cl(5) bond length is 2.63 Å. There are five inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a distorted rectangular see-saw-like geometry to one K(2), two equivalent K(1), and one Sb(1) atom. In the second Cl site, Cl(2) is bonded to one K(2), two equivalent K(1), and one Sb(1) atom to form distorted ClK3Sb tetrahedra that share corners with five equivalent Cl(3)K4Sb square pyramids, corners with five equivalent Cl(5)K3Sb tetrahedra,  an edgeedge with one Cl(3)K4Sb square pyramid, and  an edgeedge with one Cl(2)K3Sb tetrahedra. In the third Cl site, Cl(3) is bonded to two equivalent K(1), two equivalent K(2), and one Sb(1) atom to form ClK4Sb square pyramids that share corners with two equivalent Cl(3)K4Sb square pyramids,  a cornercorner with one Cl(5)K3Sb tetrahedra, corners with five equivalent Cl(2)K3Sb tetrahedra,  an edgeedge with one Cl(3)K4Sb square pyramid,  an edgeedge with one Cl(2)K3Sb tetrahedra, and edges with three equivalent Cl(5)K3Sb tetrahedra. In the fourth Cl site, Cl(4) is bonded in a rectangular see-saw-like geometry to one K(2), two equivalent K(1), and one Sb(1) atom. In the fifth Cl site, Cl(5) is bonded to one K(1), two equivalent K(2), and one Sb(1) atom to form distorted ClK3Sb tetrahedra that share  a cornercorner with one Cl(3)K4Sb square pyramid, corners with two equivalent Cl(5)K3Sb tetrahedra, corners with five equivalent Cl(2)K3Sb tetrahedra, and edges with three equivalent Cl(3)K4Sb square pyramids.