BaCaI4 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 Ca(1)I5 trigonal bipyramids. Ca(1) is bonded to one I(1), one I(3), one I(4), and two equivalent I(2) atoms to form CaI5 trigonal bipyramids that share edges with four equivalent Ba(1)I7 pentagonal bipyramids and  an edgeedge with one Ca(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 Ca(1) atom. In the second I site, I(2) is bonded in a 3-coordinate geometry to one Ba(1) and two equivalent Ca(1) atoms. In the third I site, I(3) is bonded in a T-shaped geometry to two equivalent Ba(1) and one Ca(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 Ca(1) atom.
BaCaI4 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 Ca(1)I5 trigonal bipyramids. The Ba(1)-I(2) bond length is 3.67 Å. There is one shorter (3.55 Å) and one longer (3.58 Å) Ba(1)-I(1) bond length. There is one shorter (3.55 Å) and one longer (3.60 Å) Ba(1)-I(3) bond length. There is one shorter (3.49 Å) and one longer (3.59 Å) Ba(1)-I(4) bond length. Ca(1) is bonded to one I(1), one I(3), one I(4), and two equivalent I(2) atoms to form CaI5 trigonal bipyramids that share edges with four equivalent Ba(1)I7 pentagonal bipyramids and  an edgeedge with one Ca(1)I5 trigonal bipyramid. The Ca(1)-I(1) bond length is 3.04 Å. The Ca(1)-I(3) bond length is 3.10 Å. The Ca(1)-I(4) bond length is 3.07 Å. There is one shorter (3.09 Å) and one longer (3.16 Å) Ca(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 Ca(1) atom. In the second I site, I(2) is bonded in a 3-coordinate geometry to one Ba(1) and two equivalent Ca(1) atoms. In the third I site, I(3) is bonded in a T-shaped geometry to two equivalent Ba(1) and one Ca(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 Ca(1) atom.