Sr3LaCl9 crystallizes in the monoclinic Pc space group. There are six inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one Cl(1), one Cl(10), one Cl(13), one Cl(14), one Cl(4), one Cl(5), and one Cl(9) atom to form distorted SrCl7 pentagonal bipyramids that share corners with two equivalent Sr(6)Cl7 pentagonal bipyramids, corners with two equivalent La(2)Cl7 pentagonal bipyramids,  an edgeedge with one Sr(3)Cl7 pentagonal bipyramid, and edges with two equivalent Sr(6)Cl7 pentagonal bipyramids. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to one Cl(11), one Cl(12), one Cl(15), one Cl(2), one Cl(3), one Cl(6), one Cl(7), and one Cl(8) atom. In the third Sr site, Sr(3) is bonded to one Cl(12), one Cl(13), one Cl(17), one Cl(18), one Cl(3), one Cl(8), and one Cl(9) atom to form distorted SrCl7 pentagonal bipyramids that share corners with two equivalent Sr(6)Cl7 pentagonal bipyramids, corners with two equivalent La(2)Cl7 pentagonal bipyramids,  an edgeedge with one Sr(1)Cl7 pentagonal bipyramid, and edges with two equivalent La(2)Cl7 pentagonal bipyramids. In the fourth Sr site, Sr(4) is bonded in a 8-coordinate geometry to one Cl(1), one Cl(10), one Cl(11), one Cl(14), one Cl(15), one Cl(16), one Cl(2), and one Cl(7) atom. In the fifth Sr site, Sr(5) is bonded in a 8-coordinate geometry to one Cl(11), one Cl(12), one Cl(15), one Cl(16), one Cl(17), one Cl(2), one Cl(3), and one Cl(6) atom. In the sixth Sr site, Sr(6) is bonded to one Cl(1), one Cl(10), one Cl(13), one Cl(14), one Cl(18), one Cl(4), and one Cl(5) atom to form distorted SrCl7 pentagonal bipyramids that share corners with two equivalent Sr(1)Cl7 pentagonal bipyramids, corners with two equivalent Sr(3)Cl7 pentagonal bipyramids,  an edgeedge with one La(2)Cl7 pentagonal bipyramid, and edges with two equivalent Sr(1)Cl7 pentagonal bipyramids. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to one Cl(1), one Cl(10), one Cl(11), one Cl(16), one Cl(2), one Cl(5), one Cl(6), and one Cl(7) atom. In the second La site, La(2) is bonded to one Cl(12), one Cl(17), one Cl(18), one Cl(3), one Cl(4), one Cl(8), and one Cl(9) atom to form distorted LaCl7 pentagonal bipyramids that share corners with two equivalent Sr(1)Cl7 pentagonal bipyramids, corners with two equivalent Sr(3)Cl7 pentagonal bipyramids,  an edgeedge with one Sr(6)Cl7 pentagonal bipyramid, and edges with two equivalent Sr(3)Cl7 pentagonal bipyramids. There are eighteen inequivalent Cl sites. In the first Cl site, Cl(1) is bonded to one Sr(1), one Sr(4), one Sr(6), and one La(1) atom to form a mixture of corner and edge-sharing ClSr3La tetrahedra. In the second Cl site, Cl(2) is bonded to one Sr(2), one Sr(4), one Sr(5), and one La(1) atom to form a mixture of distorted corner and edge-sharing ClSr3La tetrahedra. In the third Cl site, Cl(3) is bonded to one Sr(2), one Sr(3), one Sr(5), and one La(2) atom to form a mixture of corner and edge-sharing ClSr3La tetrahedra. In the fourth Cl site, Cl(4) is bonded in a trigonal non-coplanar geometry to one Sr(1), one Sr(6), and one La(2) atom. In the fifth Cl site, Cl(5) is bonded in a trigonal planar geometry to one Sr(1), one Sr(6), and one La(1) atom. In the sixth Cl site, Cl(6) is bonded in a distorted trigonal non-coplanar geometry to one Sr(2), one Sr(5), and one La(1) atom. In the seventh Cl site, Cl(7) is bonded in a distorted trigonal non-coplanar geometry to one Sr(2), one Sr(4), and one La(1) atom. In the eighth Cl site, Cl(8) is bonded in a trigonal planar geometry to one Sr(2), one Sr(3), and one La(2) atom. In the ninth Cl site, Cl(9) is bonded in a trigonal non-coplanar geometry to one Sr(1), one Sr(3), and one La(2) atom. In the tenth Cl site, Cl(10) is bonded to one Sr(1), one Sr(4), one Sr(6), and one La(1) atom to form a mixture of corner and edge-sharing ClSr3La tetrahedra. In the eleventh Cl site, Cl(11) is bonded to one Sr(2), one Sr(4), one Sr(5), and one La(1) atom to form a mixture of corner and edge-sharing ClSr3La tetrahedra. In the twelfth Cl site, Cl(12) is bonded to one Sr(2), one Sr(3), one Sr(5), and one La(2) atom to form a mixture of corner and edge-sharing ClSr3La tetrahedra. In the thirteenth Cl site, Cl(13) is bonded in a trigonal non-coplanar geometry to one Sr(1), one Sr(3), and one Sr(6) atom. In the fourteenth Cl site, Cl(14) is bonded in a trigonal planar geometry to one Sr(1), one Sr(4), and one Sr(6) atom. In the fifteenth Cl site, Cl(15) is bonded in a distorted trigonal non-coplanar geometry to one Sr(2), one Sr(4), and one Sr(5) atom. In the sixteenth Cl site, Cl(16) is bonded in a distorted trigonal non-coplanar geometry to one Sr(4), one Sr(5), and one La(1) atom. In the seventeenth Cl site, Cl(17) is bonded in a trigonal planar geometry to one Sr(3), one Sr(5), and one La(2) atom. In the eighteenth Cl site, Cl(18) is bonded in a trigonal non-coplanar geometry to one Sr(3), one Sr(6), and one La(2) atom.
Sr3LaCl9 crystallizes in the monoclinic Pc space group. There are six inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one Cl(1), one Cl(10), one Cl(13), one Cl(14), one Cl(4), one Cl(5), and one Cl(9) atom to form distorted SrCl7 pentagonal bipyramids that share corners with two equivalent Sr(6)Cl7 pentagonal bipyramids, corners with two equivalent La(2)Cl7 pentagonal bipyramids,  an edgeedge with one Sr(3)Cl7 pentagonal bipyramid, and edges with two equivalent Sr(6)Cl7 pentagonal bipyramids. The Sr(1)-Cl(1) bond length is 3.12 Å. The Sr(1)-Cl(10) bond length is 3.04 Å. The Sr(1)-Cl(13) bond length is 2.95 Å. The Sr(1)-Cl(14) bond length is 2.92 Å. The Sr(1)-Cl(4) bond length is 2.98 Å. The Sr(1)-Cl(5) bond length is 2.97 Å. The Sr(1)-Cl(9) bond length is 2.99 Å. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to one Cl(11), one Cl(12), one Cl(15), one Cl(2), one Cl(3), one Cl(6), one Cl(7), and one Cl(8) atom. The Sr(2)-Cl(11) bond length is 3.06 Å. The Sr(2)-Cl(12) bond length is 3.13 Å. The Sr(2)-Cl(15) bond length is 2.89 Å. The Sr(2)-Cl(2) bond length is 3.03 Å. The Sr(2)-Cl(3) bond length is 3.08 Å. The Sr(2)-Cl(6) bond length is 2.91 Å. The Sr(2)-Cl(7) bond length is 3.17 Å. The Sr(2)-Cl(8) bond length is 3.03 Å. In the third Sr site, Sr(3) is bonded to one Cl(12), one Cl(13), one Cl(17), one Cl(18), one Cl(3), one Cl(8), and one Cl(9) atom to form distorted SrCl7 pentagonal bipyramids that share corners with two equivalent Sr(6)Cl7 pentagonal bipyramids, corners with two equivalent La(2)Cl7 pentagonal bipyramids,  an edgeedge with one Sr(1)Cl7 pentagonal bipyramid, and edges with two equivalent La(2)Cl7 pentagonal bipyramids. The Sr(3)-Cl(12) bond length is 3.06 Å. The Sr(3)-Cl(13) bond length is 2.91 Å. The Sr(3)-Cl(17) bond length is 2.95 Å. The Sr(3)-Cl(18) bond length is 2.98 Å. The Sr(3)-Cl(3) bond length is 3.11 Å. The Sr(3)-Cl(8) bond length is 3.00 Å. The Sr(3)-Cl(9) bond length is 3.03 Å. In the fourth Sr site, Sr(4) is bonded in a 8-coordinate geometry to one Cl(1), one Cl(10), one Cl(11), one Cl(14), one Cl(15), one Cl(16), one Cl(2), and one Cl(7) atom. The Sr(4)-Cl(1) bond length is 3.05 Å. The Sr(4)-Cl(10) bond length is 3.17 Å. The Sr(4)-Cl(11) bond length is 3.06 Å. The Sr(4)-Cl(14) bond length is 2.93 Å. The Sr(4)-Cl(15) bond length is 3.32 Å. The Sr(4)-Cl(16) bond length is 2.95 Å. The Sr(4)-Cl(2) bond length is 3.00 Å. The Sr(4)-Cl(7) bond length is 2.92 Å. In the fifth Sr site, Sr(5) is bonded in a 8-coordinate geometry to one Cl(11), one Cl(12), one Cl(15), one Cl(16), one Cl(17), one Cl(2), one Cl(3), and one Cl(6) atom. The Sr(5)-Cl(11) bond length is 3.03 Å. The Sr(5)-Cl(12) bond length is 3.10 Å. The Sr(5)-Cl(15) bond length is 2.90 Å. The Sr(5)-Cl(16) bond length is 3.19 Å. The Sr(5)-Cl(17) bond length is 3.01 Å. The Sr(5)-Cl(2) bond length is 3.13 Å. The Sr(5)-Cl(3) bond length is 3.21 Å. The Sr(5)-Cl(6) bond length is 2.90 Å. In the sixth Sr site, Sr(6) is bonded to one Cl(1), one Cl(10), one Cl(13), one Cl(14), one Cl(18), one Cl(4), and one Cl(5) atom to form distorted SrCl7 pentagonal bipyramids that share corners with two equivalent Sr(1)Cl7 pentagonal bipyramids, corners with two equivalent Sr(3)Cl7 pentagonal bipyramids,  an edgeedge with one La(2)Cl7 pentagonal bipyramid, and edges with two equivalent Sr(1)Cl7 pentagonal bipyramids. The Sr(6)-Cl(1) bond length is 3.06 Å. The Sr(6)-Cl(10) bond length is 3.18 Å. The Sr(6)-Cl(13) bond length is 2.91 Å. The Sr(6)-Cl(14) bond length is 2.89 Å. The Sr(6)-Cl(18) bond length is 3.02 Å. The Sr(6)-Cl(4) bond length is 3.01 Å. The Sr(6)-Cl(5) bond length is 2.99 Å. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to one Cl(1), one Cl(10), one Cl(11), one Cl(16), one Cl(2), one Cl(5), one Cl(6), and one Cl(7) atom. The La(1)-Cl(1) bond length is 3.02 Å. The La(1)-Cl(10) bond length is 2.96 Å. The La(1)-Cl(11) bond length is 2.98 Å. The La(1)-Cl(16) bond length is 2.82 Å. The La(1)-Cl(2) bond length is 2.97 Å. The La(1)-Cl(5) bond length is 2.90 Å. The La(1)-Cl(6) bond length is 3.05 Å. The La(1)-Cl(7) bond length is 2.80 Å. In the second La site, La(2) is bonded to one Cl(12), one Cl(17), one Cl(18), one Cl(3), one Cl(4), one Cl(8), and one Cl(9) atom to form distorted LaCl7 pentagonal bipyramids that share corners with two equivalent Sr(1)Cl7 pentagonal bipyramids, corners with two equivalent Sr(3)Cl7 pentagonal bipyramids,  an edgeedge with one Sr(6)Cl7 pentagonal bipyramid, and edges with two equivalent Sr(3)Cl7 pentagonal bipyramids. The La(2)-Cl(12) bond length is 3.01 Å. The La(2)-Cl(17) bond length is 2.85 Å. The La(2)-Cl(18) bond length is 2.87 Å. The La(2)-Cl(3) bond length is 2.93 Å. The La(2)-Cl(4) bond length is 2.84 Å. The La(2)-Cl(8) bond length is 2.84 Å. The La(2)-Cl(9) bond length is 2.84 Å. There are eighteen inequivalent Cl sites. In the first Cl site, Cl(1) is bonded to one Sr(1), one Sr(4), one Sr(6), and one La(1) atom to form a mixture of corner and edge-sharing ClSr3La tetrahedra. In the second Cl site, Cl(2) is bonded to one Sr(2), one Sr(4), one Sr(5), and one La(1) atom to form a mixture of distorted corner and edge-sharing ClSr3La tetrahedra. In the third Cl site, Cl(3) is bonded to one Sr(2), one Sr(3), one Sr(5), and one La(2) atom to form a mixture of corner and edge-sharing ClSr3La tetrahedra. In the fourth Cl site, Cl(4) is bonded in a trigonal non-coplanar geometry to one Sr(1), one Sr(6), and one La(2) atom. In the fifth Cl site, Cl(5) is bonded in a trigonal planar geometry to one Sr(1), one Sr(6), and one La(1) atom. In the sixth Cl site, Cl(6) is bonded in a distorted trigonal non-coplanar geometry to one Sr(2), one Sr(5), and one La(1) atom. In the seventh Cl site, Cl(7) is bonded in a distorted trigonal non-coplanar geometry to one Sr(2), one Sr(4), and one La(1) atom. In the eighth Cl site, Cl(8) is bonded in a trigonal planar geometry to one Sr(2), one Sr(3), and one La(2) atom. In the ninth Cl site, Cl(9) is bonded in a trigonal non-coplanar geometry to one Sr(1), one Sr(3), and one La(2) atom. In the tenth Cl site, Cl(10) is bonded to one Sr(1), one Sr(4), one Sr(6), and one La(1) atom to form a mixture of corner and edge-sharing ClSr3La tetrahedra. In the eleventh Cl site, Cl(11) is bonded to one Sr(2), one Sr(4), one Sr(5), and one La(1) atom to form a mixture of corner and edge-sharing ClSr3La tetrahedra. In the twelfth Cl site, Cl(12) is bonded to one Sr(2), one Sr(3), one Sr(5), and one La(2) atom to form a mixture of corner and edge-sharing ClSr3La tetrahedra. In the thirteenth Cl site, Cl(13) is bonded in a trigonal non-coplanar geometry to one Sr(1), one Sr(3), and one Sr(6) atom. In the fourteenth Cl site, Cl(14) is bonded in a trigonal planar geometry to one Sr(1), one Sr(4), and one Sr(6) atom. In the fifteenth Cl site, Cl(15) is bonded in a distorted trigonal non-coplanar geometry to one Sr(2), one Sr(4), and one Sr(5) atom. In the sixteenth Cl site, Cl(16) is bonded in a distorted trigonal non-coplanar geometry to one Sr(4), one Sr(5), and one La(1) atom. In the seventeenth Cl site, Cl(17) is bonded in a trigonal planar geometry to one Sr(3), one Sr(5), and one La(2) atom. In the eighteenth Cl site, Cl(18) is bonded in a trigonal non-coplanar geometry to one Sr(3), one Sr(6), and one La(2) atom.