RbBi3Se5 crystallizes in the orthorhombic Pnma space group. Rb(1) is bonded in a 8-coordinate geometry to one Se(5), two equivalent Se(1), two equivalent Se(4), and three equivalent Se(2) atoms. There are three inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one Se(3), two equivalent Se(1), and three equivalent Se(5) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 4-9°. In the second Bi site, Bi(2) is bonded to one Se(4), one Se(5), two equivalent Se(2), and two equivalent Se(3) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 4-9°. In the third Bi site, Bi(3) is bonded to one Se(1), two equivalent Se(4), and three equivalent Se(3) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 4°. There are five inequivalent Se sites. In the first Se site, Se(5) is bonded to one Rb(1), one Bi(2), and three equivalent Bi(1) atoms to form SeRbBi4 trigonal bipyramids that share  a cornercorner with one Se(3)Bi6 octahedra, corners with three equivalent Se(4)Rb2Bi3 square pyramids, corners with two equivalent Se(1)Rb2Bi3 trigonal bipyramids, corners with two equivalent Se(5)RbBi4 trigonal bipyramids, edges with two equivalent Se(3)Bi6 octahedra, edges with two equivalent Se(5)RbBi4 trigonal bipyramids, and edges with three equivalent Se(1)Rb2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 2°. In the second Se site, Se(1) is bonded to two equivalent Rb(1), one Bi(3), and two equivalent Bi(1) atoms to form distorted SeRb2Bi3 trigonal bipyramids that share  a cornercorner with one Se(3)Bi6 octahedra, corners with four equivalent Se(4)Rb2Bi3 square pyramids, corners with two equivalent Se(5)RbBi4 trigonal bipyramids, edges with two equivalent Se(3)Bi6 octahedra,  an edgeedge with one Se(4)Rb2Bi3 square pyramid, edges with two equivalent Se(1)Rb2Bi3 trigonal bipyramids, and edges with three equivalent Se(5)RbBi4 trigonal bipyramids. The corner-sharing octahedral tilt angles are 5°. In the third Se site, Se(2) is bonded in a 5-coordinate geometry to three equivalent Rb(1) and two equivalent Bi(2) atoms. In the fourth Se site, Se(3) is bonded to one Bi(1), two equivalent Bi(2), and three equivalent Bi(3) atoms to form SeBi6 octahedra that share corners with two equivalent Se(4)Rb2Bi3 square pyramids,  a cornercorner with one Se(1)Rb2Bi3 trigonal bipyramid,  a cornercorner with one Se(5)RbBi4 trigonal bipyramid, edges with four equivalent Se(3)Bi6 octahedra, edges with three equivalent Se(4)Rb2Bi3 square pyramids, edges with two equivalent Se(1)Rb2Bi3 trigonal bipyramids, and edges with two equivalent Se(5)RbBi4 trigonal bipyramids. In the fifth Se site, Se(4) is bonded to two equivalent Rb(1), one Bi(2), and two equivalent Bi(3) atoms to form SeRb2Bi3 square pyramids that share corners with two equivalent Se(3)Bi6 octahedra, corners with three equivalent Se(5)RbBi4 trigonal bipyramids, corners with four equivalent Se(1)Rb2Bi3 trigonal bipyramids, edges with three equivalent Se(3)Bi6 octahedra, edges with two equivalent Se(4)Rb2Bi3 square pyramids, and  an edgeedge with one Se(1)Rb2Bi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 7°.
RbBi3Se5 crystallizes in the orthorhombic Pnma space group. Rb(1) is bonded in a 8-coordinate geometry to one Se(5), two equivalent Se(1), two equivalent Se(4), and three equivalent Se(2) atoms. The Rb(1)-Se(5) bond length is 3.49 Å. Both Rb(1)-Se(1) bond lengths are 3.79 Å. Both Rb(1)-Se(4) bond lengths are 3.56 Å. There is one shorter (3.54 Å) and two longer (3.84 Å) Rb(1)-Se(2) bond lengths. There are three inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one Se(3), two equivalent Se(1), and three equivalent Se(5) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 4-9°. The Bi(1)-Se(3) bond length is 2.97 Å. Both Bi(1)-Se(1) bond lengths are 2.96 Å. There is one shorter (2.88 Å) and two longer (2.95 Å) Bi(1)-Se(5) bond lengths. In the second Bi site, Bi(2) is bonded to one Se(4), one Se(5), two equivalent Se(2), and two equivalent Se(3) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 4-9°. The Bi(2)-Se(4) bond length is 2.86 Å. The Bi(2)-Se(5) bond length is 3.07 Å. Both Bi(2)-Se(2) bond lengths are 2.79 Å. Both Bi(2)-Se(3) bond lengths are 3.24 Å. In the third Bi site, Bi(3) is bonded to one Se(1), two equivalent Se(4), and three equivalent Se(3) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 4°. The Bi(3)-Se(1) bond length is 2.79 Å. Both Bi(3)-Se(4) bond lengths are 2.91 Å. There are two shorter (3.02 Å) and one longer (3.15 Å) Bi(3)-Se(3) bond length. There are five inequivalent Se sites. In the first Se site, Se(5) is bonded to one Rb(1), one Bi(2), and three equivalent Bi(1) atoms to form SeRbBi4 trigonal bipyramids that share  a cornercorner with one Se(3)Bi6 octahedra, corners with three equivalent Se(4)Rb2Bi3 square pyramids, corners with two equivalent Se(1)Rb2Bi3 trigonal bipyramids, corners with two equivalent Se(5)RbBi4 trigonal bipyramids, edges with two equivalent Se(3)Bi6 octahedra, edges with two equivalent Se(5)RbBi4 trigonal bipyramids, and edges with three equivalent Se(1)Rb2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 2°. In the second Se site, Se(1) is bonded to two equivalent Rb(1), one Bi(3), and two equivalent Bi(1) atoms to form distorted SeRb2Bi3 trigonal bipyramids that share  a cornercorner with one Se(3)Bi6 octahedra, corners with four equivalent Se(4)Rb2Bi3 square pyramids, corners with two equivalent Se(5)RbBi4 trigonal bipyramids, edges with two equivalent Se(3)Bi6 octahedra,  an edgeedge with one Se(4)Rb2Bi3 square pyramid, edges with two equivalent Se(1)Rb2Bi3 trigonal bipyramids, and edges with three equivalent Se(5)RbBi4 trigonal bipyramids. The corner-sharing octahedral tilt angles are 5°. In the third Se site, Se(2) is bonded in a 5-coordinate geometry to three equivalent Rb(1) and two equivalent Bi(2) atoms. In the fourth Se site, Se(3) is bonded to one Bi(1), two equivalent Bi(2), and three equivalent Bi(3) atoms to form SeBi6 octahedra that share corners with two equivalent Se(4)Rb2Bi3 square pyramids,  a cornercorner with one Se(1)Rb2Bi3 trigonal bipyramid,  a cornercorner with one Se(5)RbBi4 trigonal bipyramid, edges with four equivalent Se(3)Bi6 octahedra, edges with three equivalent Se(4)Rb2Bi3 square pyramids, edges with two equivalent Se(1)Rb2Bi3 trigonal bipyramids, and edges with two equivalent Se(5)RbBi4 trigonal bipyramids. In the fifth Se site, Se(4) is bonded to two equivalent Rb(1), one Bi(2), and two equivalent Bi(3) atoms to form SeRb2Bi3 square pyramids that share corners with two equivalent Se(3)Bi6 octahedra, corners with three equivalent Se(5)RbBi4 trigonal bipyramids, corners with four equivalent Se(1)Rb2Bi3 trigonal bipyramids, edges with three equivalent Se(3)Bi6 octahedra, edges with two equivalent Se(4)Rb2Bi3 square pyramids, and  an edgeedge with one Se(1)Rb2Bi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 7°.