K3Bi2I9 crystallizes in the monoclinic C2/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to two equivalent I(2) and two equivalent I(4) atoms. In the second K site, K(2) is bonded in a 6-coordinate geometry to one I(2), one I(4), two equivalent I(1), and two equivalent I(3) atoms. Bi(1) is bonded to one I(1), one I(3), one I(4), one I(5), and two equivalent I(2) atoms to form face-sharing BiI6 octahedra. There are five inequivalent I sites. In the first I site, I(5) is bonded in a distorted L-shaped geometry to two equivalent Bi(1) atoms. In the second I site, I(1) is bonded in a distorted T-shaped geometry to two equivalent K(2) and one Bi(1) atom. In the third I site, I(2) is bonded in a rectangular see-saw-like geometry to one K(1), one K(2), and two equivalent Bi(1) atoms. In the fourth I site, I(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(2) and one Bi(1) atom. In the fifth I site, I(4) is bonded in a distorted trigonal non-coplanar geometry to one K(1), one K(2), and one Bi(1) atom.
K3Bi2I9 crystallizes in the monoclinic C2/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to two equivalent I(2) and two equivalent I(4) atoms. Both K(1)-I(2) bond lengths are 3.63 Å. Both K(1)-I(4) bond lengths are 3.55 Å. In the second K site, K(2) is bonded in a 6-coordinate geometry to one I(2), one I(4), two equivalent I(1), and two equivalent I(3) atoms. The K(2)-I(2) bond length is 3.58 Å. The K(2)-I(4) bond length is 3.58 Å. There is one shorter (3.56 Å) and one longer (3.72 Å) K(2)-I(1) bond length. There is one shorter (3.58 Å) and one longer (3.65 Å) K(2)-I(3) bond length. Bi(1) is bonded to one I(1), one I(3), one I(4), one I(5), and two equivalent I(2) atoms to form face-sharing BiI6 octahedra. The Bi(1)-I(1) bond length is 2.96 Å. The Bi(1)-I(3) bond length is 3.02 Å. The Bi(1)-I(4) bond length is 2.99 Å. The Bi(1)-I(5) bond length is 3.19 Å. There is one shorter (3.23 Å) and one longer (3.30 Å) Bi(1)-I(2) bond length. There are five inequivalent I sites. In the first I site, I(5) is bonded in a distorted L-shaped geometry to two equivalent Bi(1) atoms. In the second I site, I(1) is bonded in a distorted T-shaped geometry to two equivalent K(2) and one Bi(1) atom. In the third I site, I(2) is bonded in a rectangular see-saw-like geometry to one K(1), one K(2), and two equivalent Bi(1) atoms. In the fourth I site, I(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(2) and one Bi(1) atom. In the fifth I site, I(4) is bonded in a distorted trigonal non-coplanar geometry to one K(1), one K(2), and one Bi(1) atom.