KPb2Br5 crystallizes in the monoclinic P2_1/c space group. K(1) is bonded in a 8-coordinate geometry to two equivalent Br(1), two equivalent Br(2), two equivalent Br(3), and two equivalent Br(5) atoms. There are two inequivalent Pb sites. In the first Pb site, Pb(1) is bonded in a 7-coordinate geometry to one Br(2), two equivalent Br(1), two equivalent Br(3), and two equivalent Br(4) atoms. In the second Pb site, Pb(2) is bonded in a 7-coordinate geometry to one Br(1), one Br(2), one Br(3), two equivalent Br(4), and two equivalent Br(5) atoms. There are five inequivalent Br sites. In the first Br site, Br(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Pb(2), and two equivalent Pb(1) atoms. In the second Br site, Br(2) is bonded to two equivalent K(1), one Pb(1), and one Pb(2) atom to form BrK2Pb2 trigonal pyramids that share corners with five equivalent Br(3)K2Pb3 trigonal bipyramids, corners with two equivalent Br(2)K2Pb2 trigonal pyramids, corners with two equivalent Br(5)K2Pb2 trigonal pyramids, corners with two equivalent Br(4)Pb4 trigonal pyramids,  an edgeedge with one Br(3)K2Pb3 trigonal bipyramid,  an edgeedge with one Br(4)Pb4 trigonal pyramid, and edges with two equivalent Br(5)K2Pb2 trigonal pyramids. In the third Br site, Br(3) is bonded to two equivalent K(1), one Pb(2), and two equivalent Pb(1) atoms to form distorted BrK2Pb3 trigonal bipyramids that share corners with four equivalent Br(5)K2Pb2 trigonal pyramids, corners with four equivalent Br(4)Pb4 trigonal pyramids, corners with five equivalent Br(2)K2Pb2 trigonal pyramids, edges with two equivalent Br(3)K2Pb3 trigonal bipyramids,  an edgeedge with one Br(2)K2Pb2 trigonal pyramid,  an edgeedge with one Br(5)K2Pb2 trigonal pyramid, and  an edgeedge with one Br(4)Pb4 trigonal pyramid. In the fourth Br site, Br(4) is bonded to two equivalent Pb(1) and two equivalent Pb(2) atoms to form distorted BrPb4 trigonal pyramids that share corners with four equivalent Br(3)K2Pb3 trigonal bipyramids, corners with two equivalent Br(2)K2Pb2 trigonal pyramids, corners with two equivalent Br(4)Pb4 trigonal pyramids, corners with four equivalent Br(5)K2Pb2 trigonal pyramids,  an edgeedge with one Br(3)K2Pb3 trigonal bipyramid,  an edgeedge with one Br(2)K2Pb2 trigonal pyramid, and  an edgeedge with one Br(4)Pb4 trigonal pyramid. In the fifth Br site, Br(5) is bonded to two equivalent K(1) and two equivalent Pb(2) atoms to form distorted BrK2Pb2 trigonal pyramids that share corners with four equivalent Br(3)K2Pb3 trigonal bipyramids, corners with two equivalent Br(2)K2Pb2 trigonal pyramids, corners with two equivalent Br(5)K2Pb2 trigonal pyramids, corners with four equivalent Br(4)Pb4 trigonal pyramids,  an edgeedge with one Br(3)K2Pb3 trigonal bipyramid,  an edgeedge with one Br(5)K2Pb2 trigonal pyramid, and edges with two equivalent Br(2)K2Pb2 trigonal pyramids.
KPb2Br5 crystallizes in the monoclinic P2_1/c space group. K(1) is bonded in a 8-coordinate geometry to two equivalent Br(1), two equivalent Br(2), two equivalent Br(3), and two equivalent Br(5) atoms. There is one shorter (3.42 Å) and one longer (3.43 Å) K(1)-Br(1) bond length. There is one shorter (3.47 Å) and one longer (3.56 Å) K(1)-Br(2) bond length. There is one shorter (3.44 Å) and one longer (3.54 Å) K(1)-Br(3) bond length. There is one shorter (3.39 Å) and one longer (3.45 Å) K(1)-Br(5) bond length. There are two inequivalent Pb sites. In the first Pb site, Pb(1) is bonded in a 7-coordinate geometry to one Br(2), two equivalent Br(1), two equivalent Br(3), and two equivalent Br(4) atoms. The Pb(1)-Br(2) bond length is 3.01 Å. There is one shorter (3.13 Å) and one longer (3.41 Å) Pb(1)-Br(1) bond length. There is one shorter (3.06 Å) and one longer (3.18 Å) Pb(1)-Br(3) bond length. There is one shorter (3.02 Å) and one longer (3.30 Å) Pb(1)-Br(4) bond length. In the second Pb site, Pb(2) is bonded in a 7-coordinate geometry to one Br(1), one Br(2), one Br(3), two equivalent Br(4), and two equivalent Br(5) atoms. The Pb(2)-Br(1) bond length is 3.13 Å. The Pb(2)-Br(2) bond length is 3.04 Å. The Pb(2)-Br(3) bond length is 3.32 Å. There is one shorter (3.12 Å) and one longer (3.14 Å) Pb(2)-Br(4) bond length. There is one shorter (2.99 Å) and one longer (3.04 Å) Pb(2)-Br(5) bond length. There are five inequivalent Br sites. In the first Br site, Br(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Pb(2), and two equivalent Pb(1) atoms. In the second Br site, Br(2) is bonded to two equivalent K(1), one Pb(1), and one Pb(2) atom to form BrK2Pb2 trigonal pyramids that share corners with five equivalent Br(3)K2Pb3 trigonal bipyramids, corners with two equivalent Br(2)K2Pb2 trigonal pyramids, corners with two equivalent Br(5)K2Pb2 trigonal pyramids, corners with two equivalent Br(4)Pb4 trigonal pyramids,  an edgeedge with one Br(3)K2Pb3 trigonal bipyramid,  an edgeedge with one Br(4)Pb4 trigonal pyramid, and edges with two equivalent Br(5)K2Pb2 trigonal pyramids. In the third Br site, Br(3) is bonded to two equivalent K(1), one Pb(2), and two equivalent Pb(1) atoms to form distorted BrK2Pb3 trigonal bipyramids that share corners with four equivalent Br(5)K2Pb2 trigonal pyramids, corners with four equivalent Br(4)Pb4 trigonal pyramids, corners with five equivalent Br(2)K2Pb2 trigonal pyramids, edges with two equivalent Br(3)K2Pb3 trigonal bipyramids,  an edgeedge with one Br(2)K2Pb2 trigonal pyramid,  an edgeedge with one Br(5)K2Pb2 trigonal pyramid, and  an edgeedge with one Br(4)Pb4 trigonal pyramid. In the fourth Br site, Br(4) is bonded to two equivalent Pb(1) and two equivalent Pb(2) atoms to form distorted BrPb4 trigonal pyramids that share corners with four equivalent Br(3)K2Pb3 trigonal bipyramids, corners with two equivalent Br(2)K2Pb2 trigonal pyramids, corners with two equivalent Br(4)Pb4 trigonal pyramids, corners with four equivalent Br(5)K2Pb2 trigonal pyramids,  an edgeedge with one Br(3)K2Pb3 trigonal bipyramid,  an edgeedge with one Br(2)K2Pb2 trigonal pyramid, and  an edgeedge with one Br(4)Pb4 trigonal pyramid. In the fifth Br site, Br(5) is bonded to two equivalent K(1) and two equivalent Pb(2) atoms to form distorted BrK2Pb2 trigonal pyramids that share corners with four equivalent Br(3)K2Pb3 trigonal bipyramids, corners with two equivalent Br(2)K2Pb2 trigonal pyramids, corners with two equivalent Br(5)K2Pb2 trigonal pyramids, corners with four equivalent Br(4)Pb4 trigonal pyramids,  an edgeedge with one Br(3)K2Pb3 trigonal bipyramid,  an edgeedge with one Br(5)K2Pb2 trigonal pyramid, and edges with two equivalent Br(2)K2Pb2 trigonal pyramids.