Co3I is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to four equivalent Co(2) and four equivalent I(1) atoms to form distorted CoCo4I4 cuboctahedra that share corners with eight equivalent Co(1)Co4I4 cuboctahedra, corners with eight equivalent Co(2)Co8I4 cuboctahedra, corners with eight equivalent I(1)Co12 cuboctahedra, edges with four equivalent Co(2)Co8I4 cuboctahedra, edges with four equivalent I(1)Co12 cuboctahedra, edges with twelve equivalent Co(1)Co4I4 cuboctahedra, and faces with six equivalent Co(1)Co4I4 cuboctahedra. In the second Co site, Co(2) is bonded to eight equivalent Co(1) and four equivalent I(1) atoms to form distorted CoCo8I4 cuboctahedra that share corners with four equivalent Co(2)Co8I4 cuboctahedra, corners with eight equivalent I(1)Co12 cuboctahedra, corners with sixteen equivalent Co(1)Co4I4 cuboctahedra, edges with eight equivalent Co(1)Co4I4 cuboctahedra, edges with eight equivalent Co(2)Co8I4 cuboctahedra, faces with four equivalent Co(2)Co8I4 cuboctahedra, and faces with six equivalent I(1)Co12 cuboctahedra. I(1) is bonded to four equivalent Co(2) and eight equivalent Co(1) atoms to form ICo12 cuboctahedra that share corners with four equivalent I(1)Co12 cuboctahedra, corners with eight equivalent Co(2)Co8I4 cuboctahedra, corners with sixteen equivalent Co(1)Co4I4 cuboctahedra, edges with eight equivalent Co(1)Co4I4 cuboctahedra, edges with eight equivalent I(1)Co12 cuboctahedra, faces with four equivalent I(1)Co12 cuboctahedra, and faces with six equivalent Co(2)Co8I4 cuboctahedra.
Co3I is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to four equivalent Co(2) and four equivalent I(1) atoms to form distorted CoCo4I4 cuboctahedra that share corners with eight equivalent Co(1)Co4I4 cuboctahedra, corners with eight equivalent Co(2)Co8I4 cuboctahedra, corners with eight equivalent I(1)Co12 cuboctahedra, edges with four equivalent Co(2)Co8I4 cuboctahedra, edges with four equivalent I(1)Co12 cuboctahedra, edges with twelve equivalent Co(1)Co4I4 cuboctahedra, and faces with six equivalent Co(1)Co4I4 cuboctahedra. All Co(1)-Co(2) bond lengths are 2.67 Å. All Co(1)-I(1) bond lengths are 2.67 Å. In the second Co site, Co(2) is bonded to eight equivalent Co(1) and four equivalent I(1) atoms to form distorted CoCo8I4 cuboctahedra that share corners with four equivalent Co(2)Co8I4 cuboctahedra, corners with eight equivalent I(1)Co12 cuboctahedra, corners with sixteen equivalent Co(1)Co4I4 cuboctahedra, edges with eight equivalent Co(1)Co4I4 cuboctahedra, edges with eight equivalent Co(2)Co8I4 cuboctahedra, faces with four equivalent Co(2)Co8I4 cuboctahedra, and faces with six equivalent I(1)Co12 cuboctahedra. All Co(2)-I(1) bond lengths are 2.69 Å. I(1) is bonded to four equivalent Co(2) and eight equivalent Co(1) atoms to form ICo12 cuboctahedra that share corners with four equivalent I(1)Co12 cuboctahedra, corners with eight equivalent Co(2)Co8I4 cuboctahedra, corners with sixteen equivalent Co(1)Co4I4 cuboctahedra, edges with eight equivalent Co(1)Co4I4 cuboctahedra, edges with eight equivalent I(1)Co12 cuboctahedra, faces with four equivalent I(1)Co12 cuboctahedra, and faces with six equivalent Co(2)Co8I4 cuboctahedra.