BaCa2I6 is Rutile-derived structured and crystallizes in the tetragonal P4_2/mnm space group. Ba(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form BaI6 octahedra that share corners with eight equivalent Ca(1)I6 octahedra and edges with two equivalent Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 51-53°. Ca(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form CaI6 octahedra that share corners with four equivalent Ba(1)I6 octahedra, corners with four equivalent Ca(1)I6 octahedra,  an edgeedge with one Ba(1)I6 octahedra, and  an edgeedge with one Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. There are two inequivalent I sites. In the first I site, I(2) is bonded in a trigonal planar geometry to one Ba(1) and two equivalent Ca(1) atoms. In the second I site, I(1) is bonded in a distorted trigonal planar geometry to one Ba(1) and two equivalent Ca(1) atoms.
BaCa2I6 is Rutile-derived structured and crystallizes in the tetragonal P4_2/mnm space group. Ba(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form BaI6 octahedra that share corners with eight equivalent Ca(1)I6 octahedra and edges with two equivalent Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 51-53°. Both Ba(1)-I(2) bond lengths are 3.46 Å. All Ba(1)-I(1) bond lengths are 3.46 Å. Ca(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form CaI6 octahedra that share corners with four equivalent Ba(1)I6 octahedra, corners with four equivalent Ca(1)I6 octahedra,  an edgeedge with one Ba(1)I6 octahedra, and  an edgeedge with one Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. Both Ca(1)-I(2) bond lengths are 3.17 Å. There are two shorter (3.16 Å) and two longer (3.21 Å) Ca(1)-I(1) bond lengths. There are two inequivalent I sites. In the first I site, I(2) is bonded in a trigonal planar geometry to one Ba(1) and two equivalent Ca(1) atoms. In the second I site, I(1) is bonded in a distorted trigonal planar geometry to one Ba(1) and two equivalent Ca(1) atoms.