SrCa2I6 is Rutile-derived structured and crystallizes in the trigonal P321 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to three equivalent I(2) and three equivalent I(3) atoms to form SrI6 octahedra that share corners with six equivalent Ca(1)I6 octahedra and edges with three equivalent Ca(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 53-55°. In the second Sr site, Sr(2) is bonded to six equivalent I(1) atoms to form SrI6 octahedra that share corners with six equivalent Ca(2)I6 octahedra and edges with three equivalent Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles are 58°. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form CaI6 octahedra that share corners with four equivalent Sr(1)I6 octahedra, corners with six equivalent Ca(2)I6 octahedra, and  an edgeedge with one Sr(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 46-55°. In the second Ca site, Ca(2) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form CaI6 octahedra that share corners with two equivalent Sr(2)I6 octahedra, corners with six equivalent Ca(1)I6 octahedra, and edges with two equivalent Sr(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 46-58°. There are three inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to one Sr(2), one Ca(1), and one Ca(2) atom. In the second I site, I(2) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ca(1), and one Ca(2) atom. In the third I site, I(3) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ca(1), and one Ca(2) atom.
SrCa2I6 is Rutile-derived structured and crystallizes in the trigonal P321 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to three equivalent I(2) and three equivalent I(3) atoms to form SrI6 octahedra that share corners with six equivalent Ca(1)I6 octahedra and edges with three equivalent Ca(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 53-55°. All Sr(1)-I(2) bond lengths are 3.28 Å. All Sr(1)-I(3) bond lengths are 3.29 Å. In the second Sr site, Sr(2) is bonded to six equivalent I(1) atoms to form SrI6 octahedra that share corners with six equivalent Ca(2)I6 octahedra and edges with three equivalent Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles are 58°. All Sr(2)-I(1) bond lengths are 3.29 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form CaI6 octahedra that share corners with four equivalent Sr(1)I6 octahedra, corners with six equivalent Ca(2)I6 octahedra, and  an edgeedge with one Sr(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 46-55°. Both Ca(1)-I(1) bond lengths are 3.18 Å. Both Ca(1)-I(2) bond lengths are 3.19 Å. Both Ca(1)-I(3) bond lengths are 3.17 Å. In the second Ca site, Ca(2) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form CaI6 octahedra that share corners with two equivalent Sr(2)I6 octahedra, corners with six equivalent Ca(1)I6 octahedra, and edges with two equivalent Sr(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 46-58°. Both Ca(2)-I(1) bond lengths are 3.17 Å. Both Ca(2)-I(2) bond lengths are 3.16 Å. Both Ca(2)-I(3) bond lengths are 3.19 Å. There are three inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to one Sr(2), one Ca(1), and one Ca(2) atom. In the second I site, I(2) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ca(1), and one Ca(2) atom. In the third I site, I(3) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ca(1), and one Ca(2) atom.