Bi4Rb5 crystallizes in the monoclinic Cm space group. There are five inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to two equivalent Bi(1), two equivalent Bi(4), and three equivalent Bi(3) atoms. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to two equivalent Bi(2), two equivalent Bi(3), and three equivalent Bi(4) atoms. In the third Rb site, Rb(3) is bonded in a 6-coordinate geometry to one Bi(2), two equivalent Bi(3), and three equivalent Bi(1) atoms. In the fourth Rb site, Rb(4) is bonded in a 6-coordinate geometry to one Bi(1), two equivalent Bi(4), and three equivalent Bi(2) atoms. In the fifth Rb site, Rb(5) is bonded in a distorted square co-planar geometry to two equivalent Bi(1) and two equivalent Bi(2) atoms. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 9-coordinate geometry to one Rb(4), two equivalent Rb(1), two equivalent Rb(5), three equivalent Rb(3), and one Bi(3) atom. In the second Bi site, Bi(2) is bonded in a 9-coordinate geometry to one Rb(3), two equivalent Rb(2), two equivalent Rb(5), three equivalent Rb(4), and one Bi(4) atom. In the third Bi site, Bi(3) is bonded in a 9-coordinate geometry to two equivalent Rb(2), two equivalent Rb(3), three equivalent Rb(1), one Bi(1), and one Bi(4) atom. In the fourth Bi site, Bi(4) is bonded in a 9-coordinate geometry to two equivalent Rb(1), two equivalent Rb(4), three equivalent Rb(2), one Bi(2), and one Bi(3) atom.
Bi4Rb5 crystallizes in the monoclinic Cm space group. There are five inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to two equivalent Bi(1), two equivalent Bi(4), and three equivalent Bi(3) atoms. Both Rb(1)-Bi(1) bond lengths are 3.89 Å. Both Rb(1)-Bi(4) bond lengths are 3.89 Å. There is one shorter (3.89 Å) and two longer (3.98 Å) Rb(1)-Bi(3) bond lengths. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to two equivalent Bi(2), two equivalent Bi(3), and three equivalent Bi(4) atoms. Both Rb(2)-Bi(2) bond lengths are 3.89 Å. Both Rb(2)-Bi(3) bond lengths are 3.88 Å. There is one shorter (3.89 Å) and two longer (3.98 Å) Rb(2)-Bi(4) bond lengths. In the third Rb site, Rb(3) is bonded in a 6-coordinate geometry to one Bi(2), two equivalent Bi(3), and three equivalent Bi(1) atoms. The Rb(3)-Bi(2) bond length is 4.03 Å. Both Rb(3)-Bi(3) bond lengths are 3.95 Å. There are two shorter (3.92 Å) and one longer (3.98 Å) Rb(3)-Bi(1) bond length. In the fourth Rb site, Rb(4) is bonded in a 6-coordinate geometry to one Bi(1), two equivalent Bi(4), and three equivalent Bi(2) atoms. The Rb(4)-Bi(1) bond length is 4.03 Å. Both Rb(4)-Bi(4) bond lengths are 3.94 Å. There are two shorter (3.90 Å) and one longer (4.01 Å) Rb(4)-Bi(2) bond length. In the fifth Rb site, Rb(5) is bonded in a distorted square co-planar geometry to two equivalent Bi(1) and two equivalent Bi(2) atoms. Both Rb(5)-Bi(1) bond lengths are 3.79 Å. Both Rb(5)-Bi(2) bond lengths are 3.79 Å. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 9-coordinate geometry to one Rb(4), two equivalent Rb(1), two equivalent Rb(5), three equivalent Rb(3), and one Bi(3) atom. The Bi(1)-Bi(3) bond length is 2.98 Å. In the second Bi site, Bi(2) is bonded in a 9-coordinate geometry to one Rb(3), two equivalent Rb(2), two equivalent Rb(5), three equivalent Rb(4), and one Bi(4) atom. The Bi(2)-Bi(4) bond length is 2.99 Å. In the third Bi site, Bi(3) is bonded in a 9-coordinate geometry to two equivalent Rb(2), two equivalent Rb(3), three equivalent Rb(1), one Bi(1), and one Bi(4) atom. The Bi(3)-Bi(4) bond length is 3.02 Å. In the fourth Bi site, Bi(4) is bonded in a 9-coordinate geometry to two equivalent Rb(1), two equivalent Rb(4), three equivalent Rb(2), one Bi(2), and one Bi(3) atom.