Rb3LaBr6 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one Br(1), one Br(3), one Br(5), one Br(6), two equivalent Br(2), and two equivalent Br(4) atoms. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one Br(2), one Br(3), one Br(5), two equivalent Br(1), and two equivalent Br(6) atoms. In the third Rb site, Rb(3) is bonded in a 8-coordinate geometry to one Br(1), one Br(2), one Br(5), one Br(6), two equivalent Br(3), and two equivalent Br(4) atoms. There are two inequivalent La sites. In the first La site, La(1) is bonded in an octahedral geometry to two equivalent Br(2), two equivalent Br(3), and two equivalent Br(4) atoms. In the second La site, La(2) is bonded in an octahedral geometry to two equivalent Br(1), two equivalent Br(5), and two equivalent Br(6) atoms. There are six inequivalent Br sites. In the first Br site, Br(5) is bonded to one Rb(1), one Rb(2), one Rb(3), and one La(2) atom to form distorted BrRb3La trigonal pyramids that share corners with two equivalent Br(1)Rb4La square pyramids, corners with two equivalent Br(3)Rb4La trigonal bipyramids, corners with two equivalent Br(4)Rb4La trigonal bipyramids,  a cornercorner with one Br(5)Rb3La trigonal pyramid, edges with two equivalent Br(1)Rb4La square pyramids,  an edgeedge with one Br(3)Rb4La trigonal bipyramid, and  an edgeedge with one Br(4)Rb4La trigonal bipyramid. In the second Br site, Br(6) is bonded in a 5-coordinate geometry to one Rb(1), one Rb(3), two equivalent Rb(2), and one La(2) atom. In the third Br site, Br(1) is bonded to one Rb(1), one Rb(3), two equivalent Rb(2), and one La(2) atom to form distorted BrRb4La square pyramids that share corners with three equivalent Br(1)Rb4La square pyramids, corners with two equivalent Br(3)Rb4La trigonal bipyramids, corners with four equivalent Br(4)Rb4La trigonal bipyramids, corners with two equivalent Br(5)Rb3La trigonal pyramids, edges with two equivalent Br(5)Rb3La trigonal pyramids, and  a faceface with one Br(3)Rb4La trigonal bipyramid. In the fourth Br site, Br(2) is bonded in a 5-coordinate geometry to one Rb(2), one Rb(3), two equivalent Rb(1), and one La(1) atom. In the fifth Br site, Br(3) is bonded to one Rb(1), one Rb(2), two equivalent Rb(3), and one La(1) atom to form distorted BrRb4La trigonal bipyramids that share corners with two equivalent Br(1)Rb4La square pyramids, corners with two equivalent Br(4)Rb4La trigonal bipyramids, corners with three equivalent Br(3)Rb4La trigonal bipyramids, corners with two equivalent Br(5)Rb3La trigonal pyramids, edges with three equivalent Br(4)Rb4La trigonal bipyramids,  an edgeedge with one Br(5)Rb3La trigonal pyramid, and  a faceface with one Br(1)Rb4La square pyramid. In the sixth Br site, Br(4) is bonded to two equivalent Rb(1), two equivalent Rb(3), and one La(1) atom to form distorted BrRb4La trigonal bipyramids that share corners with four equivalent Br(1)Rb4La square pyramids,  a cornercorner with one Br(4)Rb4La trigonal bipyramid, corners with two equivalent Br(3)Rb4La trigonal bipyramids, corners with two equivalent Br(5)Rb3La trigonal pyramids, edges with two equivalent Br(4)Rb4La trigonal bipyramids, edges with three equivalent Br(3)Rb4La trigonal bipyramids, and  an edgeedge with one Br(5)Rb3La trigonal pyramid.
Rb3LaBr6 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one Br(1), one Br(3), one Br(5), one Br(6), two equivalent Br(2), and two equivalent Br(4) atoms. The Rb(1)-Br(1) bond length is 3.55 Å. The Rb(1)-Br(3) bond length is 3.40 Å. The Rb(1)-Br(5) bond length is 3.29 Å. The Rb(1)-Br(6) bond length is 3.92 Å. There is one shorter (3.72 Å) and one longer (3.87 Å) Rb(1)-Br(2) bond length. There is one shorter (3.52 Å) and one longer (3.54 Å) Rb(1)-Br(4) bond length. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one Br(2), one Br(3), one Br(5), two equivalent Br(1), and two equivalent Br(6) atoms. The Rb(2)-Br(2) bond length is 4.05 Å. The Rb(2)-Br(3) bond length is 3.66 Å. The Rb(2)-Br(5) bond length is 3.48 Å. There is one shorter (3.61 Å) and one longer (3.91 Å) Rb(2)-Br(1) bond length. There is one shorter (3.50 Å) and one longer (3.78 Å) Rb(2)-Br(6) bond length. In the third Rb site, Rb(3) is bonded in a 8-coordinate geometry to one Br(1), one Br(2), one Br(5), one Br(6), two equivalent Br(3), and two equivalent Br(4) atoms. The Rb(3)-Br(1) bond length is 3.70 Å. The Rb(3)-Br(2) bond length is 3.47 Å. The Rb(3)-Br(5) bond length is 3.48 Å. The Rb(3)-Br(6) bond length is 3.56 Å. There is one shorter (3.64 Å) and one longer (3.87 Å) Rb(3)-Br(3) bond length. There is one shorter (3.48 Å) and one longer (3.53 Å) Rb(3)-Br(4) bond length. There are two inequivalent La sites. In the first La site, La(1) is bonded in an octahedral geometry to two equivalent Br(2), two equivalent Br(3), and two equivalent Br(4) atoms. Both La(1)-Br(2) bond lengths are 2.93 Å. Both La(1)-Br(3) bond lengths are 2.95 Å. Both La(1)-Br(4) bond lengths are 2.97 Å. In the second La site, La(2) is bonded in an octahedral geometry to two equivalent Br(1), two equivalent Br(5), and two equivalent Br(6) atoms. Both La(2)-Br(1) bond lengths are 2.90 Å. Both La(2)-Br(5) bond lengths are 2.91 Å. Both La(2)-Br(6) bond lengths are 2.99 Å. There are six inequivalent Br sites. In the first Br site, Br(5) is bonded to one Rb(1), one Rb(2), one Rb(3), and one La(2) atom to form distorted BrRb3La trigonal pyramids that share corners with two equivalent Br(1)Rb4La square pyramids, corners with two equivalent Br(3)Rb4La trigonal bipyramids, corners with two equivalent Br(4)Rb4La trigonal bipyramids,  a cornercorner with one Br(5)Rb3La trigonal pyramid, edges with two equivalent Br(1)Rb4La square pyramids,  an edgeedge with one Br(3)Rb4La trigonal bipyramid, and  an edgeedge with one Br(4)Rb4La trigonal bipyramid. In the second Br site, Br(6) is bonded in a 5-coordinate geometry to one Rb(1), one Rb(3), two equivalent Rb(2), and one La(2) atom. In the third Br site, Br(1) is bonded to one Rb(1), one Rb(3), two equivalent Rb(2), and one La(2) atom to form distorted BrRb4La square pyramids that share corners with three equivalent Br(1)Rb4La square pyramids, corners with two equivalent Br(3)Rb4La trigonal bipyramids, corners with four equivalent Br(4)Rb4La trigonal bipyramids, corners with two equivalent Br(5)Rb3La trigonal pyramids, edges with two equivalent Br(5)Rb3La trigonal pyramids, and  a faceface with one Br(3)Rb4La trigonal bipyramid. In the fourth Br site, Br(2) is bonded in a 5-coordinate geometry to one Rb(2), one Rb(3), two equivalent Rb(1), and one La(1) atom. In the fifth Br site, Br(3) is bonded to one Rb(1), one Rb(2), two equivalent Rb(3), and one La(1) atom to form distorted BrRb4La trigonal bipyramids that share corners with two equivalent Br(1)Rb4La square pyramids, corners with two equivalent Br(4)Rb4La trigonal bipyramids, corners with three equivalent Br(3)Rb4La trigonal bipyramids, corners with two equivalent Br(5)Rb3La trigonal pyramids, edges with three equivalent Br(4)Rb4La trigonal bipyramids,  an edgeedge with one Br(5)Rb3La trigonal pyramid, and  a faceface with one Br(1)Rb4La square pyramid. In the sixth Br site, Br(4) is bonded to two equivalent Rb(1), two equivalent Rb(3), and one La(1) atom to form distorted BrRb4La trigonal bipyramids that share corners with four equivalent Br(1)Rb4La square pyramids,  a cornercorner with one Br(4)Rb4La trigonal bipyramid, corners with two equivalent Br(3)Rb4La trigonal bipyramids, corners with two equivalent Br(5)Rb3La trigonal pyramids, edges with two equivalent Br(4)Rb4La trigonal bipyramids, edges with three equivalent Br(3)Rb4La trigonal bipyramids, and  an edgeedge with one Br(5)Rb3La trigonal pyramid.