SrCaI4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one I(3), one I(4), two equivalent I(1), and two equivalent I(5) atoms to form SrI6 octahedra that share corners with two equivalent Ca(1)I6 octahedra, corners with two equivalent Ca(2)I6 octahedra,  an edgeedge with one Ca(1)I6 octahedra, edges with two equivalent Sr(2)I6 octahedra, and edges with two equivalent Ca(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 10-19°. In the second Sr site, Sr(2) is bonded to two equivalent I(2), two equivalent I(3), and two equivalent I(5) atoms to form SrI6 octahedra that share corners with two equivalent Ca(1)I6 octahedra, corners with two equivalent Ca(2)I6 octahedra,  an edgeedge with one Sr(2)I6 octahedra, edges with two equivalent Sr(1)I6 octahedra, and edges with two equivalent Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 10-18°. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one I(3), one I(4), two equivalent I(2), and two equivalent I(5) atoms to form CaI6 octahedra that share corners with two equivalent Sr(1)I6 octahedra, corners with two equivalent Sr(2)I6 octahedra,  an edgeedge with one Sr(1)I6 octahedra, edges with two equivalent Sr(2)I6 octahedra, and edges with two equivalent Ca(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 10-19°. In the second Ca site, Ca(2) is bonded to two equivalent I(1), two equivalent I(4), and two equivalent I(5) atoms to form CaI6 octahedra that share corners with two equivalent Sr(1)I6 octahedra, corners with two equivalent Sr(2)I6 octahedra,  an edgeedge with one Ca(2)I6 octahedra, edges with two equivalent Sr(1)I6 octahedra, and edges with two equivalent Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 10-18°. There are five inequivalent I sites. In the first I site, I(1) is bonded in a linear geometry to one Sr(1) and one Ca(2) atom. In the second I site, I(2) is bonded in a linear geometry to one Sr(2) and one Ca(1) atom. In the third I site, I(3) is bonded in a see-saw-like geometry to one Sr(1), two equivalent Sr(2), and one Ca(1) atom. In the fourth I site, I(4) is bonded in a see-saw-like geometry to one Sr(1), one Ca(1), and two equivalent Ca(2) atoms. In the fifth I site, I(5) is bonded in a see-saw-like geometry to one Sr(1), one Sr(2), one Ca(1), and one Ca(2) atom.
SrCaI4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one I(3), one I(4), two equivalent I(1), and two equivalent I(5) atoms to form SrI6 octahedra that share corners with two equivalent Ca(1)I6 octahedra, corners with two equivalent Ca(2)I6 octahedra,  an edgeedge with one Ca(1)I6 octahedra, edges with two equivalent Sr(2)I6 octahedra, and edges with two equivalent Ca(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 10-19°. The Sr(1)-I(3) bond length is 3.38 Å. The Sr(1)-I(4) bond length is 3.37 Å. Both Sr(1)-I(1) bond lengths are 3.14 Å. Both Sr(1)-I(5) bond lengths are 3.44 Å. In the second Sr site, Sr(2) is bonded to two equivalent I(2), two equivalent I(3), and two equivalent I(5) atoms to form SrI6 octahedra that share corners with two equivalent Ca(1)I6 octahedra, corners with two equivalent Ca(2)I6 octahedra,  an edgeedge with one Sr(2)I6 octahedra, edges with two equivalent Sr(1)I6 octahedra, and edges with two equivalent Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 10-18°. Both Sr(2)-I(2) bond lengths are 3.14 Å. Both Sr(2)-I(3) bond lengths are 3.45 Å. Both Sr(2)-I(5) bond lengths are 3.37 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one I(3), one I(4), two equivalent I(2), and two equivalent I(5) atoms to form CaI6 octahedra that share corners with two equivalent Sr(1)I6 octahedra, corners with two equivalent Sr(2)I6 octahedra,  an edgeedge with one Sr(1)I6 octahedra, edges with two equivalent Sr(2)I6 octahedra, and edges with two equivalent Ca(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 10-19°. The Ca(1)-I(3) bond length is 3.24 Å. The Ca(1)-I(4) bond length is 3.24 Å. Both Ca(1)-I(2) bond lengths are 2.99 Å. Both Ca(1)-I(5) bond lengths are 3.29 Å. In the second Ca site, Ca(2) is bonded to two equivalent I(1), two equivalent I(4), and two equivalent I(5) atoms to form CaI6 octahedra that share corners with two equivalent Sr(1)I6 octahedra, corners with two equivalent Sr(2)I6 octahedra,  an edgeedge with one Ca(2)I6 octahedra, edges with two equivalent Sr(1)I6 octahedra, and edges with two equivalent Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 10-18°. Both Ca(2)-I(1) bond lengths are 2.99 Å. Both Ca(2)-I(4) bond lengths are 3.29 Å. Both Ca(2)-I(5) bond lengths are 3.24 Å. There are five inequivalent I sites. In the first I site, I(1) is bonded in a linear geometry to one Sr(1) and one Ca(2) atom. In the second I site, I(2) is bonded in a linear geometry to one Sr(2) and one Ca(1) atom. In the third I site, I(3) is bonded in a see-saw-like geometry to one Sr(1), two equivalent Sr(2), and one Ca(1) atom. In the fourth I site, I(4) is bonded in a see-saw-like geometry to one Sr(1), one Ca(1), and two equivalent Ca(2) atoms. In the fifth I site, I(5) is bonded in a see-saw-like geometry to one Sr(1), one Sr(2), one Ca(1), and one Ca(2) atom.