BaSr2I6 is trigonal omega-derived structured and crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form BaI6 octahedra that share corners with four equivalent Sr(1)I6 pentagonal pyramids and edges with four equivalent Sr(1)I6 pentagonal pyramids. Sr(1) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form distorted SrI6 pentagonal pyramids that share corners with two equivalent Ba(1)I6 octahedra, corners with two equivalent Sr(1)I6 pentagonal pyramids, edges with two equivalent Ba(1)I6 octahedra, and edges with two equivalent Sr(1)I6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 48-76°. There are three inequivalent I sites. In the first I site, I(1) is bonded in a T-shaped geometry to one Ba(1) and two equivalent Sr(1) atoms. 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 one Ba(1) and two equivalent Sr(1) atoms.
BaSr2I6 is trigonal omega-derived structured and crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form BaI6 octahedra that share corners with four equivalent Sr(1)I6 pentagonal pyramids and edges with four equivalent Sr(1)I6 pentagonal pyramids. Both Ba(1)-I(1) bond lengths are 3.47 Å. Both Ba(1)-I(2) bond lengths are 3.41 Å. Both Ba(1)-I(3) bond lengths are 3.49 Å. Sr(1) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form distorted SrI6 pentagonal pyramids that share corners with two equivalent Ba(1)I6 octahedra, corners with two equivalent Sr(1)I6 pentagonal pyramids, edges with two equivalent Ba(1)I6 octahedra, and edges with two equivalent Sr(1)I6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 48-76°. There is one shorter (3.32 Å) and one longer (3.34 Å) Sr(1)-I(1) bond length. There is one shorter (3.33 Å) and one longer (3.38 Å) Sr(1)-I(2) bond length. There is one shorter (3.37 Å) and one longer (3.39 Å) Sr(1)-I(3) bond length. There are three inequivalent I sites. In the first I site, I(1) is bonded in a T-shaped geometry to one Ba(1) and two equivalent Sr(1) atoms. 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 one Ba(1) and two equivalent Sr(1) atoms.