SrCa2I6 is Hydrophilite-derived structured and crystallizes in the orthorhombic P2_12_12_1 space group. Sr(1) is bonded to one I(1), one I(2), one I(3), one I(4), one I(5), and one I(6) atom to form SrI6 octahedra that share corners with four equivalent Ca(2)I6 octahedra, corners with two equivalent Ca(1)I6 pentagonal pyramids,  an edgeedge with one Ca(2)I6 octahedra, and edges with two equivalent Ca(1)I6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 38-63°. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one I(2), one I(3), one I(4), one I(6), and two equivalent I(1) atoms to form distorted CaI6 pentagonal pyramids that share corners with two equivalent Sr(1)I6 octahedra, corners with four equivalent Ca(2)I6 octahedra, corners with two equivalent Ca(1)I6 pentagonal pyramids, and edges with two equivalent Sr(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 29-70°. In the second Ca site, Ca(2) is bonded to one I(2), one I(3), one I(4), one I(6), and two equivalent I(5) atoms to form CaI6 octahedra that share corners with two equivalent Ca(2)I6 octahedra, corners with four equivalent Sr(1)I6 octahedra, corners with four equivalent Ca(1)I6 pentagonal pyramids, and  an edgeedge with one Sr(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 38-63°. There are six inequivalent I sites. In the first I site, I(1) is bonded in a 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 T-shaped geometry to one Sr(1), one Ca(1), and one Ca(2) atom. In the fourth I site, I(4) is bonded in a distorted T-shaped geometry to one Sr(1), one Ca(1), and one Ca(2) atom. In the fifth I site, I(5) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Ca(2) atoms. In the sixth I site, I(6) is bonded in a T-shaped geometry to one Sr(1), one Ca(1), and one Ca(2) atom.
SrCa2I6 is Hydrophilite-derived structured and crystallizes in the orthorhombic P2_12_12_1 space group. Sr(1) is bonded to one I(1), one I(2), one I(3), one I(4), one I(5), and one I(6) atom to form SrI6 octahedra that share corners with four equivalent Ca(2)I6 octahedra, corners with two equivalent Ca(1)I6 pentagonal pyramids,  an edgeedge with one Ca(2)I6 octahedra, and edges with two equivalent Ca(1)I6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 38-63°. The Sr(1)-I(1) bond length is 3.32 Å. The Sr(1)-I(2) bond length is 3.20 Å. The Sr(1)-I(3) bond length is 3.29 Å. The Sr(1)-I(4) bond length is 3.27 Å. The Sr(1)-I(5) bond length is 3.38 Å. The Sr(1)-I(6) bond length is 3.23 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one I(2), one I(3), one I(4), one I(6), and two equivalent I(1) atoms to form distorted CaI6 pentagonal pyramids that share corners with two equivalent Sr(1)I6 octahedra, corners with four equivalent Ca(2)I6 octahedra, corners with two equivalent Ca(1)I6 pentagonal pyramids, and edges with two equivalent Sr(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 29-70°. The Ca(1)-I(2) bond length is 3.23 Å. The Ca(1)-I(3) bond length is 3.26 Å. The Ca(1)-I(4) bond length is 3.29 Å. The Ca(1)-I(6) bond length is 3.15 Å. There is one shorter (3.14 Å) and one longer (3.18 Å) Ca(1)-I(1) bond length. In the second Ca site, Ca(2) is bonded to one I(2), one I(3), one I(4), one I(6), and two equivalent I(5) atoms to form CaI6 octahedra that share corners with two equivalent Ca(2)I6 octahedra, corners with four equivalent Sr(1)I6 octahedra, corners with four equivalent Ca(1)I6 pentagonal pyramids, and  an edgeedge with one Sr(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 38-63°. The Ca(2)-I(2) bond length is 3.17 Å. The Ca(2)-I(3) bond length is 3.27 Å. The Ca(2)-I(4) bond length is 3.18 Å. The Ca(2)-I(6) bond length is 3.18 Å. There is one shorter (3.21 Å) and one longer (3.23 Å) Ca(2)-I(5) bond length. There are six inequivalent I sites. In the first I site, I(1) is bonded in a 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 T-shaped geometry to one Sr(1), one Ca(1), and one Ca(2) atom. In the fourth I site, I(4) is bonded in a distorted T-shaped geometry to one Sr(1), one Ca(1), and one Ca(2) atom. In the fifth I site, I(5) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Ca(2) atoms. In the sixth I site, I(6) is bonded in a T-shaped geometry to one Sr(1), one Ca(1), and one Ca(2) atom.