BaSr2I6 is Fluorite-derived structured and crystallizes in the orthorhombic Cmce space group. Ba(1) is bonded in a body-centered cubic geometry to eight equivalent I(1) atoms. Sr(1) is bonded in a body-centered cubic geometry to four equivalent I(1) and four equivalent I(2) atoms. There are two inequivalent I sites. In the first I site, I(2) is bonded to four equivalent Sr(1) atoms to form ISr4 tetrahedra that share corners with four equivalent I(2)Sr4 tetrahedra, corners with twelve equivalent I(1)Ba2Sr2 tetrahedra, edges with two equivalent I(1)Ba2Sr2 tetrahedra, and edges with four equivalent I(2)Sr4 tetrahedra. In the second I site, I(1) is bonded to two equivalent Ba(1) and two equivalent Sr(1) atoms to form IBa2Sr2 tetrahedra that share corners with six equivalent I(2)Sr4 tetrahedra, corners with ten equivalent I(1)Ba2Sr2 tetrahedra,  an edgeedge with one I(2)Sr4 tetrahedra, and edges with five equivalent I(1)Ba2Sr2 tetrahedra.
BaSr2I6 is Fluorite-derived structured and crystallizes in the orthorhombic Cmce space group. Ba(1) is bonded in a body-centered cubic geometry to eight equivalent I(1) atoms. There are four shorter (3.58 Å) and four longer (3.61 Å) Ba(1)-I(1) bond lengths. Sr(1) is bonded in a body-centered cubic geometry to four equivalent I(1) and four equivalent I(2) atoms. There are two shorter (3.49 Å) and two longer (3.53 Å) Sr(1)-I(1) bond lengths. There are two shorter (3.44 Å) and two longer (3.60 Å) Sr(1)-I(2) bond lengths. There are two inequivalent I sites. In the first I site, I(2) is bonded to four equivalent Sr(1) atoms to form ISr4 tetrahedra that share corners with four equivalent I(2)Sr4 tetrahedra, corners with twelve equivalent I(1)Ba2Sr2 tetrahedra, edges with two equivalent I(1)Ba2Sr2 tetrahedra, and edges with four equivalent I(2)Sr4 tetrahedra. In the second I site, I(1) is bonded to two equivalent Ba(1) and two equivalent Sr(1) atoms to form IBa2Sr2 tetrahedra that share corners with six equivalent I(2)Sr4 tetrahedra, corners with ten equivalent I(1)Ba2Sr2 tetrahedra,  an edgeedge with one I(2)Sr4 tetrahedra, and edges with five equivalent I(1)Ba2Sr2 tetrahedra.