K3O5I crystallizes in the tetragonal P4/ncc space group. There are seven inequivalent K sites. In the first K site, K(1) is bonded to one O(1) and four equivalent O(2) atoms to form KO5 square pyramids that share corners with five I(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra. In the second K site, K(1) is bonded to one O(1) and four equivalent O(2) atoms to form KO5 square pyramids that share corners with five I(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra. In the third K site, K(1) is bonded to one O(1) and four equivalent O(2) atoms to form KO5 square pyramids that share corners with five I(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra. In the fourth K site, K(2) is bonded in a body-centered cubic geometry to eight equivalent O(2) atoms. In the fifth K site, K(2) is bonded in a body-centered cubic geometry to eight equivalent O(2) atoms. In the sixth K site, K(3) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form distorted KO12 cuboctahedra that share corners with four equivalent K(3)O12 cuboctahedra; faces with four equivalent K(3)O12 cuboctahedra; faces with four K(1,1)O5 square pyramids; and faces with four I(1,1)O5 square pyramids. In the seventh K site, K(3) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form distorted KO12 cuboctahedra that share corners with four equivalent K(3)O12 cuboctahedra; faces with four equivalent K(3)O12 cuboctahedra; faces with four K(1,1)O5 square pyramids; and faces with four I(1,1)O5 square pyramids. There are two inequivalent O sites. In the first O site, O(1) is bonded to one K(1); four K(3,3); and one I(1) atom to form a mixture of distorted corner and edge-sharing OK5I octahedra. The corner-sharing octahedral tilt angles are 6°. In the second O site, O(2) is bonded in a 6-coordinate geometry to one K(1); two K(2,2); two K(3,3); and one I(1) atom. There are three inequivalent I sites. In the first I site, I(1) is bonded to one O(1) and four equivalent O(2) atoms to form distorted IO5 square pyramids that share corners with five K(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra. In the second I site, I(1) is bonded to one O(1) and four equivalent O(2) atoms to form distorted IO5 square pyramids that share corners with five K(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra. In the third I site, I(1) is bonded to one O(1) and four equivalent O(2) atoms to form distorted IO5 square pyramids that share corners with five K(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra.
K3O5I crystallizes in the tetragonal P4/ncc space group. There are seven inequivalent K sites. In the first K site, K(1) is bonded to one O(1) and four equivalent O(2) atoms to form KO5 square pyramids that share corners with five I(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra. The K(1)-O(1) bond length is 2.51 Å. All K(1)-O(2) bond lengths are 2.59 Å. In the second K site, K(1) is bonded to one O(1) and four equivalent O(2) atoms to form KO5 square pyramids that share corners with five I(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra. The K(1)-O(1) bond length is 2.51 Å. All K(1)-O(2) bond lengths are 2.59 Å. In the third K site, K(1) is bonded to one O(1) and four equivalent O(2) atoms to form KO5 square pyramids that share corners with five I(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra. The K(1)-O(1) bond length is 2.51 Å. All K(1)-O(2) bond lengths are 2.59 Å. In the fourth K site, K(2) is bonded in a body-centered cubic geometry to eight equivalent O(2) atoms. There are four shorter (2.82 Å) and four longer (2.83 Å) K(2)-O(2) bond lengths. In the fifth K site, K(2) is bonded in a body-centered cubic geometry to eight equivalent O(2) atoms. There are four shorter (2.82 Å) and four longer (2.83 Å) K(2)-O(2) bond lengths. In the sixth K site, K(3) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form distorted KO12 cuboctahedra that share corners with four equivalent K(3)O12 cuboctahedra; faces with four equivalent K(3)O12 cuboctahedra; faces with four K(1,1)O5 square pyramids; and faces with four I(1,1)O5 square pyramids. All K(3)-O(1) bond lengths are 3.12 Å. There are four shorter (3.23 Å) and four longer (3.25 Å) K(3)-O(2) bond lengths. In the seventh K site, K(3) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form distorted KO12 cuboctahedra that share corners with four equivalent K(3)O12 cuboctahedra; faces with four equivalent K(3)O12 cuboctahedra; faces with four K(1,1)O5 square pyramids; and faces with four I(1,1)O5 square pyramids. All K(3)-O(1) bond lengths are 3.12 Å. There are four shorter (3.23 Å) and four longer (3.25 Å) K(3)-O(2) bond lengths. There are two inequivalent O sites. In the first O site, O(1) is bonded to one K(1); four K(3,3); and one I(1) atom to form a mixture of distorted corner and edge-sharing OK5I octahedra. The corner-sharing octahedral tilt angles are 6°. The O(1)-I(1) bond length is 1.80 Å. In the second O site, O(2) is bonded in a 6-coordinate geometry to one K(1); two K(2,2); two K(3,3); and one I(1) atom. The O(2)-I(1) bond length is 1.85 Å. There are three inequivalent I sites. In the first I site, I(1) is bonded to one O(1) and four equivalent O(2) atoms to form distorted IO5 square pyramids that share corners with five K(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra. In the second I site, I(1) is bonded to one O(1) and four equivalent O(2) atoms to form distorted IO5 square pyramids that share corners with five K(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra. The I(1)-O(1) bond length is 1.80 Å. All I(1)-O(2) bond lengths are 1.85 Å. In the third I site, I(1) is bonded to one O(1) and four equivalent O(2) atoms to form distorted IO5 square pyramids that share corners with five K(1,1)O5 square pyramids and faces with four K(3,3)O12 cuboctahedra. The I(1)-O(1) bond length is 1.80 Å. All I(1)-O(2) bond lengths are 1.85 Å.