BaSrI4 crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded to one I(2), two equivalent I(1), two equivalent I(3), and two equivalent I(4) atoms to form distorted BaI7 pentagonal bipyramids that share corners with four equivalent Ba(1)I7 pentagonal bipyramids,  an edgeedge with one Ba(1)I7 pentagonal bipyramid, and edges with four equivalent Sr(1)I5 trigonal bipyramids. Sr(1) is bonded to one I(1), one I(3), one I(4), and two equivalent I(2) atoms to form SrI5 trigonal bipyramids that share edges with four equivalent Ba(1)I7 pentagonal bipyramids and  an edgeedge with one Sr(1)I5 trigonal bipyramid. There are four inequivalent I sites. In the first I site, I(1) is bonded in a distorted T-shaped geometry to two equivalent Ba(1) and one Sr(1) atom. In the second I site, I(2) is bonded in a distorted T-shaped geometry to one Ba(1) and two equivalent Sr(1) atoms. In the third I site, I(3) is bonded in a T-shaped geometry to two equivalent Ba(1) and one Sr(1) atom. In the fourth I site, I(4) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ba(1) and one Sr(1) atom.
BaSrI4 crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded to one I(2), two equivalent I(1), two equivalent I(3), and two equivalent I(4) atoms to form distorted BaI7 pentagonal bipyramids that share corners with four equivalent Ba(1)I7 pentagonal bipyramids,  an edgeedge with one Ba(1)I7 pentagonal bipyramid, and edges with four equivalent Sr(1)I5 trigonal bipyramids. The Ba(1)-I(2) bond length is 3.61 Å. There is one shorter (3.57 Å) and one longer (3.62 Å) Ba(1)-I(1) bond length. There is one shorter (3.55 Å) and one longer (3.75 Å) Ba(1)-I(3) bond length. There is one shorter (3.54 Å) and one longer (3.55 Å) Ba(1)-I(4) bond length. Sr(1) is bonded to one I(1), one I(3), one I(4), and two equivalent I(2) atoms to form SrI5 trigonal bipyramids that share edges with four equivalent Ba(1)I7 pentagonal bipyramids and  an edgeedge with one Sr(1)I5 trigonal bipyramid. The Sr(1)-I(1) bond length is 3.19 Å. The Sr(1)-I(3) bond length is 3.24 Å. The Sr(1)-I(4) bond length is 3.23 Å. There is one shorter (3.25 Å) and one longer (3.30 Å) Sr(1)-I(2) bond length. There are four inequivalent I sites. In the first I site, I(1) is bonded in a distorted T-shaped geometry to two equivalent Ba(1) and one Sr(1) atom. In the second I site, I(2) is bonded in a distorted T-shaped geometry to one Ba(1) and two equivalent Sr(1) atoms. In the third I site, I(3) is bonded in a T-shaped geometry to two equivalent Ba(1) and one Sr(1) atom. In the fourth I site, I(4) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ba(1) and one Sr(1) atom.