Ba4Sm3Cl16 crystallizes in the trigonal R-3 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one Cl(2), three equivalent Cl(3), three equivalent Cl(5), and three equivalent Cl(6) atoms. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to one Cl(2), one Cl(5), one Cl(6), two equivalent Cl(3), two equivalent Cl(4), and three equivalent Cl(1) atoms. Sm(1) is bonded in a 8-coordinate geometry to one Cl(1), one Cl(3), two equivalent Cl(4), two equivalent Cl(5), and two equivalent Cl(6) atoms. There are six inequivalent Cl sites. In the first Cl site, Cl(6) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), and two equivalent Sm(1) atoms. In the second Cl site, Cl(1) is bonded to three equivalent Ba(2) and one Sm(1) atom to form ClBa3Sm tetrahedra that share  a cornercorner with one Cl(2)Ba4 tetrahedra, corners with two equivalent Cl(1)Ba3Sm tetrahedra, corners with three equivalent Cl(5)Ba2Sm2 tetrahedra, corners with five equivalent Cl(3)Ba3Sm tetrahedra,  an edgeedge with one Cl(5)Ba2Sm2 tetrahedra,  an edgeedge with one Cl(3)Ba3Sm tetrahedra,  an edgeedge with one Cl(2)Ba4 tetrahedra, and edges with two equivalent Cl(1)Ba3Sm tetrahedra. In the third Cl site, Cl(2) is bonded to one Ba(1) and three equivalent Ba(2) atoms to form ClBa4 tetrahedra that share corners with three equivalent Cl(1)Ba3Sm tetrahedra, corners with three equivalent Cl(3)Ba3Sm tetrahedra, corners with six equivalent Cl(5)Ba2Sm2 tetrahedra, edges with three equivalent Cl(1)Ba3Sm tetrahedra, and edges with three equivalent Cl(3)Ba3Sm tetrahedra. In the fourth Cl site, Cl(3) is bonded to one Ba(1), two equivalent Ba(2), and one Sm(1) atom to form ClBa3Sm tetrahedra that share  a cornercorner with one Cl(2)Ba4 tetrahedra, corners with two equivalent Cl(3)Ba3Sm tetrahedra, corners with three equivalent Cl(5)Ba2Sm2 tetrahedra, corners with five equivalent Cl(1)Ba3Sm tetrahedra,  an edgeedge with one Cl(1)Ba3Sm tetrahedra,  an edgeedge with one Cl(3)Ba3Sm tetrahedra,  an edgeedge with one Cl(2)Ba4 tetrahedra, and edges with two equivalent Cl(5)Ba2Sm2 tetrahedra. In the fifth Cl site, Cl(4) is bonded in a 4-coordinate geometry to two equivalent Ba(2) and two equivalent Sm(1) atoms. In the sixth Cl site, Cl(5) is bonded to one Ba(1), one Ba(2), and two equivalent Sm(1) atoms to form ClBa2Sm2 tetrahedra that share corners with two equivalent Cl(5)Ba2Sm2 tetrahedra, corners with two equivalent Cl(2)Ba4 tetrahedra, corners with three equivalent Cl(1)Ba3Sm tetrahedra, corners with three equivalent Cl(3)Ba3Sm tetrahedra,  an edgeedge with one Cl(5)Ba2Sm2 tetrahedra,  an edgeedge with one Cl(1)Ba3Sm tetrahedra, and edges with two equivalent Cl(3)Ba3Sm tetrahedra.
Ba4Sm3Cl16 crystallizes in the trigonal R-3 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one Cl(2), three equivalent Cl(3), three equivalent Cl(5), and three equivalent Cl(6) atoms. The Ba(1)-Cl(2) bond length is 3.45 Å. All Ba(1)-Cl(3) bond lengths are 3.16 Å. All Ba(1)-Cl(5) bond lengths are 3.10 Å. All Ba(1)-Cl(6) bond lengths are 3.65 Å. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to one Cl(2), one Cl(5), one Cl(6), two equivalent Cl(3), two equivalent Cl(4), and three equivalent Cl(1) atoms. The Ba(2)-Cl(2) bond length is 3.18 Å. The Ba(2)-Cl(5) bond length is 3.19 Å. The Ba(2)-Cl(6) bond length is 3.52 Å. There is one shorter (3.18 Å) and one longer (3.32 Å) Ba(2)-Cl(3) bond length. There is one shorter (3.44 Å) and one longer (3.56 Å) Ba(2)-Cl(4) bond length. There are a spread of Ba(2)-Cl(1) bond distances ranging from 3.15-3.40 Å. Sm(1) is bonded in a 8-coordinate geometry to one Cl(1), one Cl(3), two equivalent Cl(4), two equivalent Cl(5), and two equivalent Cl(6) atoms. The Sm(1)-Cl(1) bond length is 2.90 Å. The Sm(1)-Cl(3) bond length is 2.90 Å. Both Sm(1)-Cl(4) bond lengths are 2.86 Å. There is one shorter (2.90 Å) and one longer (2.91 Å) Sm(1)-Cl(5) bond length. There is one shorter (2.80 Å) and one longer (2.90 Å) Sm(1)-Cl(6) bond length. There are six inequivalent Cl sites. In the first Cl site, Cl(6) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), and two equivalent Sm(1) atoms. In the second Cl site, Cl(1) is bonded to three equivalent Ba(2) and one Sm(1) atom to form ClBa3Sm tetrahedra that share  a cornercorner with one Cl(2)Ba4 tetrahedra, corners with two equivalent Cl(1)Ba3Sm tetrahedra, corners with three equivalent Cl(5)Ba2Sm2 tetrahedra, corners with five equivalent Cl(3)Ba3Sm tetrahedra,  an edgeedge with one Cl(5)Ba2Sm2 tetrahedra,  an edgeedge with one Cl(3)Ba3Sm tetrahedra,  an edgeedge with one Cl(2)Ba4 tetrahedra, and edges with two equivalent Cl(1)Ba3Sm tetrahedra. In the third Cl site, Cl(2) is bonded to one Ba(1) and three equivalent Ba(2) atoms to form ClBa4 tetrahedra that share corners with three equivalent Cl(1)Ba3Sm tetrahedra, corners with three equivalent Cl(3)Ba3Sm tetrahedra, corners with six equivalent Cl(5)Ba2Sm2 tetrahedra, edges with three equivalent Cl(1)Ba3Sm tetrahedra, and edges with three equivalent Cl(3)Ba3Sm tetrahedra. In the fourth Cl site, Cl(3) is bonded to one Ba(1), two equivalent Ba(2), and one Sm(1) atom to form ClBa3Sm tetrahedra that share  a cornercorner with one Cl(2)Ba4 tetrahedra, corners with two equivalent Cl(3)Ba3Sm tetrahedra, corners with three equivalent Cl(5)Ba2Sm2 tetrahedra, corners with five equivalent Cl(1)Ba3Sm tetrahedra,  an edgeedge with one Cl(1)Ba3Sm tetrahedra,  an edgeedge with one Cl(3)Ba3Sm tetrahedra,  an edgeedge with one Cl(2)Ba4 tetrahedra, and edges with two equivalent Cl(5)Ba2Sm2 tetrahedra. In the fifth Cl site, Cl(4) is bonded in a 4-coordinate geometry to two equivalent Ba(2) and two equivalent Sm(1) atoms. In the sixth Cl site, Cl(5) is bonded to one Ba(1), one Ba(2), and two equivalent Sm(1) atoms to form ClBa2Sm2 tetrahedra that share corners with two equivalent Cl(5)Ba2Sm2 tetrahedra, corners with two equivalent Cl(2)Ba4 tetrahedra, corners with three equivalent Cl(1)Ba3Sm tetrahedra, corners with three equivalent Cl(3)Ba3Sm tetrahedra,  an edgeedge with one Cl(5)Ba2Sm2 tetrahedra,  an edgeedge with one Cl(1)Ba3Sm tetrahedra, and edges with two equivalent Cl(3)Ba3Sm tetrahedra.