SrCa2I6 is Hydrophilite-derived structured and crystallizes in the monoclinic P2_1/c space group. Sr(1) is bonded to one I(1), one I(2), one I(4), one I(5), and two equivalent I(3) atoms to form SrI6 octahedra that share corners with two equivalent Ca(1)I6 octahedra, corners with six equivalent Ca(2)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 48-59°. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one I(2), one I(5), two equivalent I(1), and two equivalent I(6) atoms to form CaI6 octahedra that share corners with two equivalent Sr(1)I6 octahedra, corners with two equivalent Ca(2)I6 octahedra, corners with four equivalent Ca(1)I6 octahedra,  an edgeedge with one Sr(1)I6 octahedra, and  an edgeedge with one Ca(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 46-59°. In the second Ca site, Ca(2) is bonded to one I(2), one I(3), one I(5), one I(6), and two equivalent I(4) atoms to form CaI6 octahedra that share corners with two equivalent Ca(1)I6 octahedra, corners with six equivalent Sr(1)I6 octahedra,  an edgeedge with one Ca(1)I6 octahedra, and  an edgeedge with one Ca(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 48-58°. There are six inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Ca(1) atoms. 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 two equivalent Sr(1) and one Ca(2) atom. In the fourth I site, I(4) is bonded in a trigonal planar geometry to one Sr(1) and two equivalent Ca(2) atoms. In the fifth I site, I(5) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ca(1), and one Ca(2) atom. In the sixth I site, I(6) is bonded in a trigonal planar geometry to one Ca(2) and two equivalent Ca(1) atoms.
SrCa2I6 is Hydrophilite-derived structured and crystallizes in the monoclinic P2_1/c space group. Sr(1) is bonded to one I(1), one I(2), one I(4), one I(5), and two equivalent I(3) atoms to form SrI6 octahedra that share corners with two equivalent Ca(1)I6 octahedra, corners with six equivalent Ca(2)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 48-59°. The Sr(1)-I(1) bond length is 3.29 Å. The Sr(1)-I(2) bond length is 3.31 Å. The Sr(1)-I(4) bond length is 3.30 Å. The Sr(1)-I(5) bond length is 3.31 Å. Both Sr(1)-I(3) bond lengths are 3.30 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one I(2), one I(5), two equivalent I(1), and two equivalent I(6) atoms to form CaI6 octahedra that share corners with two equivalent Sr(1)I6 octahedra, corners with two equivalent Ca(2)I6 octahedra, corners with four equivalent Ca(1)I6 octahedra,  an edgeedge with one Sr(1)I6 octahedra, and  an edgeedge with one Ca(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 46-59°. The Ca(1)-I(2) bond length is 3.13 Å. The Ca(1)-I(5) bond length is 3.12 Å. There is one shorter (3.16 Å) and one longer (3.22 Å) Ca(1)-I(1) bond length. There is one shorter (3.16 Å) and one longer (3.22 Å) Ca(1)-I(6) bond length. In the second Ca site, Ca(2) is bonded to one I(2), one I(3), one I(5), one I(6), and two equivalent I(4) atoms to form CaI6 octahedra that share corners with two equivalent Ca(1)I6 octahedra, corners with six equivalent Sr(1)I6 octahedra,  an edgeedge with one Ca(1)I6 octahedra, and  an edgeedge with one Ca(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 48-58°. The Ca(2)-I(2) bond length is 3.19 Å. The Ca(2)-I(3) bond length is 3.14 Å. The Ca(2)-I(5) bond length is 3.15 Å. The Ca(2)-I(6) bond length is 3.18 Å. There is one shorter (3.15 Å) and one longer (3.16 Å) Ca(2)-I(4) bond length. There are six inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Ca(1) atoms. 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 two equivalent Sr(1) and one Ca(2) atom. In the fourth I site, I(4) is bonded in a trigonal planar geometry to one Sr(1) and two equivalent Ca(2) atoms. In the fifth I site, I(5) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ca(1), and one Ca(2) atom. In the sixth I site, I(6) is bonded in a trigonal planar geometry to one Ca(2) and two equivalent Ca(1) atoms.