Ba2Ca7I18 crystallizes in the triclinic P-1 space group. Ba(1) is bonded in a 7-coordinate geometry to one I(1), one I(2), one I(3), one I(6), one I(8), and two equivalent I(9) atoms. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one I(1), one I(2), one I(4), one I(6), one I(8), and one I(9) atom to form a mixture of corner and edge-sharing CaI6 octahedra. The corner-sharing octahedral tilt angles range from 50-62°. In the second Ca site, Ca(2) is bonded to two equivalent I(3), two equivalent I(4), and two equivalent I(9) atoms to form a mixture of corner and edge-sharing CaI6 octahedra. The corner-sharing octahedral tilt angles range from 57-60°. In the third Ca site, Ca(3) is bonded to one I(1), one I(2), one I(3), one I(5), one I(7), and one I(8) atom to form a mixture of corner and edge-sharing CaI6 octahedra. The corner-sharing octahedral tilt angles range from 53-58°. In the fourth Ca site, Ca(4) is bonded to one I(4), one I(6), one I(7), one I(8), and two equivalent I(5) atoms to form a mixture of corner and edge-sharing CaI6 octahedra. The corner-sharing octahedral tilt angles range from 50-62°. There are nine inequivalent I sites. In the first I site, I(1) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ca(1), and one Ca(3) atom. In the second I site, I(2) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Ca(1), and one Ca(3) atom. In the third I site, I(3) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Ca(2), and one Ca(3) atom. In the fourth I site, I(4) is bonded in a trigonal planar geometry to one Ca(1), one Ca(2), and one Ca(4) atom. In the fifth I site, I(5) is bonded in a distorted T-shaped geometry to one Ca(3) and two equivalent Ca(4) atoms. In the sixth I site, I(6) is bonded in a distorted trigonal planar geometry to one Ba(1), one Ca(1), and one Ca(4) atom. In the seventh I site, I(7) is bonded in an L-shaped geometry to one Ca(3) and one Ca(4) atom. In the eighth I site, I(8) is bonded in a 3-coordinate geometry to one Ba(1), one Ca(1), one Ca(3), and one Ca(4) atom. In the ninth I site, I(9) is bonded to two equivalent Ba(1), one Ca(1), and one Ca(2) atom to form a mixture of distorted corner and edge-sharing IBa2Ca2 trigonal pyramids.
Ba2Ca7I18 crystallizes in the triclinic P-1 space group. Ba(1) is bonded in a 7-coordinate geometry to one I(1), one I(2), one I(3), one I(6), one I(8), and two equivalent I(9) atoms. The Ba(1)-I(1) bond length is 4.04 Å. The Ba(1)-I(2) bond length is 3.61 Å. The Ba(1)-I(3) bond length is 3.59 Å. The Ba(1)-I(6) bond length is 3.52 Å. The Ba(1)-I(8) bond length is 4.23 Å. There is one shorter (3.56 Å) and one longer (3.78 Å) Ba(1)-I(9) bond length. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one I(1), one I(2), one I(4), one I(6), one I(8), and one I(9) atom to form a mixture of corner and edge-sharing CaI6 octahedra. The corner-sharing octahedral tilt angles range from 50-62°. The Ca(1)-I(1) bond length is 3.08 Å. The Ca(1)-I(2) bond length is 3.15 Å. The Ca(1)-I(4) bond length is 3.13 Å. The Ca(1)-I(6) bond length is 3.09 Å. The Ca(1)-I(8) bond length is 3.28 Å. The Ca(1)-I(9) bond length is 3.24 Å. In the second Ca site, Ca(2) is bonded to two equivalent I(3), two equivalent I(4), and two equivalent I(9) atoms to form a mixture of corner and edge-sharing CaI6 octahedra. The corner-sharing octahedral tilt angles range from 57-60°. Both Ca(2)-I(3) bond lengths are 3.15 Å. Both Ca(2)-I(4) bond lengths are 3.12 Å. Both Ca(2)-I(9) bond lengths are 3.20 Å. In the third Ca site, Ca(3) is bonded to one I(1), one I(2), one I(3), one I(5), one I(7), and one I(8) atom to form a mixture of corner and edge-sharing CaI6 octahedra. The corner-sharing octahedral tilt angles range from 53-58°. The Ca(3)-I(1) bond length is 3.12 Å. The Ca(3)-I(2) bond length is 3.20 Å. The Ca(3)-I(3) bond length is 3.16 Å. The Ca(3)-I(5) bond length is 3.13 Å. The Ca(3)-I(7) bond length is 3.11 Å. The Ca(3)-I(8) bond length is 3.23 Å. In the fourth Ca site, Ca(4) is bonded to one I(4), one I(6), one I(7), one I(8), and two equivalent I(5) atoms to form a mixture of corner and edge-sharing CaI6 octahedra. The corner-sharing octahedral tilt angles range from 50-62°. The Ca(4)-I(4) bond length is 3.16 Å. The Ca(4)-I(6) bond length is 3.14 Å. The Ca(4)-I(7) bond length is 3.07 Å. The Ca(4)-I(8) bond length is 3.25 Å. Both Ca(4)-I(5) bond lengths are 3.14 Å. There are nine inequivalent I sites. In the first I site, I(1) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ca(1), and one Ca(3) atom. In the second I site, I(2) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Ca(1), and one Ca(3) atom. In the third I site, I(3) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Ca(2), and one Ca(3) atom. In the fourth I site, I(4) is bonded in a trigonal planar geometry to one Ca(1), one Ca(2), and one Ca(4) atom. In the fifth I site, I(5) is bonded in a distorted T-shaped geometry to one Ca(3) and two equivalent Ca(4) atoms. In the sixth I site, I(6) is bonded in a distorted trigonal planar geometry to one Ba(1), one Ca(1), and one Ca(4) atom. In the seventh I site, I(7) is bonded in an L-shaped geometry to one Ca(3) and one Ca(4) atom. In the eighth I site, I(8) is bonded in a 3-coordinate geometry to one Ba(1), one Ca(1), one Ca(3), and one Ca(4) atom. In the ninth I site, I(9) is bonded to two equivalent Ba(1), one Ca(1), and one Ca(2) atom to form a mixture of distorted corner and edge-sharing IBa2Ca2 trigonal pyramids.