SrCa2I6 is Rutile-derived structured and crystallizes in the tetragonal P4_2/mnm space group. Sr(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form SrI6 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 are 50°. 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 Sr(1)I6 octahedra, corners with four equivalent Ca(1)I6 octahedra,  an edgeedge with one Sr(1)I6 octahedra, and  an edgeedge with one Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 46-50°. There are two inequivalent I sites. In the first I site, I(2) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Ca(1) atoms. In the second I site, I(1) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Ca(1) atoms.
SrCa2I6 is Rutile-derived structured and crystallizes in the tetragonal P4_2/mnm space group. Sr(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form SrI6 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 are 50°. Both Sr(1)-I(2) bond lengths are 3.31 Å. All Sr(1)-I(1) bond lengths are 3.28 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 Sr(1)I6 octahedra, corners with four equivalent Ca(1)I6 octahedra,  an edgeedge with one Sr(1)I6 octahedra, and  an edgeedge with one Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 46-50°. Both Ca(1)-I(2) bond lengths are 3.15 Å. There are two shorter (3.16 Å) and two longer (3.19 Å) Ca(1)-I(1) bond lengths. There are two inequivalent I sites. In the first I site, I(2) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Ca(1) atoms. In the second I site, I(1) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Ca(1) atoms.