Ba2CaI6 crystallizes in the tetragonal P-4b2 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a body-centered cubic geometry to four equivalent I(2) and four equivalent I(3) atoms. In the second Ba site, Ba(2) is bonded in a body-centered cubic geometry to four equivalent I(1) and four equivalent I(3) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a tetrahedral geometry to four equivalent I(2) atoms. In the second Ca site, Ca(2) is bonded in a square co-planar geometry to four equivalent I(1) atoms. There are three inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to two equivalent Ba(2) and one Ca(2) atom. In the second I site, I(2) is bonded in a distorted trigonal planar geometry to two equivalent Ba(1) and one Ca(1) atom. In the third I site, I(3) is bonded to two equivalent Ba(1) and two equivalent Ba(2) atoms to form a mixture of corner and edge-sharing IBa4 tetrahedra.
Ba2CaI6 crystallizes in the tetragonal P-4b2 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a body-centered cubic geometry to four equivalent I(2) and four equivalent I(3) atoms. All Ba(1)-I(2) bond lengths are 3.62 Å. There are two shorter (3.55 Å) and two longer (3.67 Å) Ba(1)-I(3) bond lengths. In the second Ba site, Ba(2) is bonded in a body-centered cubic geometry to four equivalent I(1) and four equivalent I(3) atoms. There are two shorter (3.61 Å) and two longer (3.65 Å) Ba(2)-I(1) bond lengths. There are two shorter (3.59 Å) and two longer (3.63 Å) Ba(2)-I(3) bond lengths. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a tetrahedral geometry to four equivalent I(2) atoms. All Ca(1)-I(2) bond lengths are 3.09 Å. In the second Ca site, Ca(2) is bonded in a square co-planar geometry to four equivalent I(1) atoms. All Ca(2)-I(1) bond lengths are 3.12 Å. There are three inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to two equivalent Ba(2) and one Ca(2) atom. In the second I site, I(2) is bonded in a distorted trigonal planar geometry to two equivalent Ba(1) and one Ca(1) atom. In the third I site, I(3) is bonded to two equivalent Ba(1) and two equivalent Ba(2) atoms to form a mixture of corner and edge-sharing IBa4 tetrahedra.