Rb4Pb9 is Magnesium tetraboride-like structured and crystallizes in the monoclinic P2_1/m space group. There are five inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to one Pb(11), one Pb(2), one Pb(7), two equivalent Pb(10), and two equivalent Pb(3) atoms. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one Pb(1), one Pb(10), one Pb(3), one Pb(4), one Pb(5), one Pb(6), one Pb(8), and one Pb(9) atom. In the third Rb site, Rb(3) is bonded in a 8-coordinate geometry to one Pb(1), one Pb(10), one Pb(12), one Pb(5), one Pb(6), one Pb(7), one Pb(8), and one Pb(9) atom. In the fourth Rb site, Rb(4) is bonded in a 7-coordinate geometry to one Pb(12), two equivalent Pb(1), two equivalent Pb(10), two equivalent Pb(8), and two equivalent Pb(9) atoms. In the fifth Rb site, Rb(5) is bonded in a 8-coordinate geometry to one Pb(1), one Pb(11), one Pb(2), one Pb(4), one Pb(6), one Pb(7), and two equivalent Pb(3) atoms. There are twelve inequivalent Pb sites. In the first Pb site, Pb(10) is bonded in a 8-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), one Rb(4), one Pb(10), one Pb(2), one Pb(8), and one Pb(9) atom. In the second Pb site, Pb(11) is bonded in a 8-coordinate geometry to one Rb(1), two equivalent Rb(5), one Pb(5), two equivalent Pb(3), and two equivalent Pb(6) atoms. In the third Pb site, Pb(12) is bonded in a 8-coordinate geometry to one Rb(4), two equivalent Rb(3), one Pb(7), two equivalent Pb(8), and two equivalent Pb(9) atoms. In the fourth Pb site, Pb(1) is bonded in a 8-coordinate geometry to one Rb(2), one Rb(3), one Rb(4), one Rb(5), one Pb(1), one Pb(4), one Pb(5), and one Pb(6) atom. In the fifth Pb site, Pb(2) is bonded in a 8-coordinate geometry to one Rb(1), two equivalent Rb(5), one Pb(7), two equivalent Pb(10), and two equivalent Pb(9) atoms. In the sixth Pb site, Pb(3) is bonded in a 8-coordinate geometry to one Rb(1), one Rb(2), two equivalent Rb(5), one Pb(11), one Pb(3), one Pb(4), and one Pb(6) atom. In the seventh Pb site, Pb(4) is bonded in a distorted body-centered cubic geometry to two equivalent Rb(2), two equivalent Rb(5), two equivalent Pb(1), and two equivalent Pb(3) atoms. In the eighth Pb site, Pb(5) is bonded in a 9-coordinate geometry to two equivalent Rb(2), two equivalent Rb(3), one Pb(11), two equivalent Pb(1), and two equivalent Pb(6) atoms. In the ninth Pb site, Pb(6) is bonded in a 7-coordinate geometry to one Rb(2), one Rb(3), one Rb(5), one Pb(1), one Pb(11), one Pb(3), and one Pb(5) atom. In the tenth Pb site, Pb(7) is bonded in a 9-coordinate geometry to one Rb(1), two equivalent Rb(3), two equivalent Rb(5), one Pb(12), one Pb(2), and two equivalent Pb(9) atoms. In the eleventh Pb site, Pb(8) is bonded in a 7-coordinate geometry to one Rb(2), one Rb(3), one Rb(4), one Pb(10), one Pb(12), one Pb(8), and one Pb(9) atom. In the twelfth Pb site, Pb(9) is bonded in a 8-coordinate geometry to one Rb(2), one Rb(3), one Rb(4), one Pb(10), one Pb(12), one Pb(2), one Pb(7), and one Pb(8) atom.
Rb4Pb9 is Magnesium tetraboride-like structured and crystallizes in the monoclinic P2_1/m space group. There are five inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to one Pb(11), one Pb(2), one Pb(7), two equivalent Pb(10), and two equivalent Pb(3) atoms. The Rb(1)-Pb(11) bond length is 3.88 Å. The Rb(1)-Pb(2) bond length is 3.74 Å. The Rb(1)-Pb(7) bond length is 3.73 Å. Both Rb(1)-Pb(10) bond lengths are 3.79 Å. Both Rb(1)-Pb(3) bond lengths are 3.81 Å. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one Pb(1), one Pb(10), one Pb(3), one Pb(4), one Pb(5), one Pb(6), one Pb(8), and one Pb(9) atom. The Rb(2)-Pb(1) bond length is 3.94 Å. The Rb(2)-Pb(10) bond length is 3.87 Å. The Rb(2)-Pb(3) bond length is 4.22 Å. The Rb(2)-Pb(4) bond length is 4.04 Å. The Rb(2)-Pb(5) bond length is 4.08 Å. The Rb(2)-Pb(6) bond length is 3.79 Å. The Rb(2)-Pb(8) bond length is 4.01 Å. The Rb(2)-Pb(9) bond length is 4.05 Å. In the third Rb site, Rb(3) is bonded in a 8-coordinate geometry to one Pb(1), one Pb(10), one Pb(12), one Pb(5), one Pb(6), one Pb(7), one Pb(8), and one Pb(9) atom. The Rb(3)-Pb(1) bond length is 3.77 Å. The Rb(3)-Pb(10) bond length is 3.78 Å. The Rb(3)-Pb(12) bond length is 3.99 Å. The Rb(3)-Pb(5) bond length is 3.97 Å. The Rb(3)-Pb(6) bond length is 4.02 Å. The Rb(3)-Pb(7) bond length is 4.04 Å. The Rb(3)-Pb(8) bond length is 3.79 Å. The Rb(3)-Pb(9) bond length is 3.73 Å. In the fourth Rb site, Rb(4) is bonded in a 7-coordinate geometry to one Pb(12), two equivalent Pb(1), two equivalent Pb(10), two equivalent Pb(8), and two equivalent Pb(9) atoms. The Rb(4)-Pb(12) bond length is 3.90 Å. Both Rb(4)-Pb(1) bond lengths are 3.95 Å. Both Rb(4)-Pb(10) bond lengths are 3.92 Å. Both Rb(4)-Pb(8) bond lengths are 3.91 Å. Both Rb(4)-Pb(9) bond lengths are 4.38 Å. In the fifth Rb site, Rb(5) is bonded in a 8-coordinate geometry to one Pb(1), one Pb(11), one Pb(2), one Pb(4), one Pb(6), one Pb(7), and two equivalent Pb(3) atoms. The Rb(5)-Pb(1) bond length is 3.76 Å. The Rb(5)-Pb(11) bond length is 4.21 Å. The Rb(5)-Pb(2) bond length is 3.90 Å. The Rb(5)-Pb(4) bond length is 3.82 Å. The Rb(5)-Pb(6) bond length is 3.79 Å. The Rb(5)-Pb(7) bond length is 4.08 Å. There is one shorter (3.86 Å) and one longer (4.23 Å) Rb(5)-Pb(3) bond length. There are twelve inequivalent Pb sites. In the first Pb site, Pb(10) is bonded in a 8-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), one Rb(4), one Pb(10), one Pb(2), one Pb(8), and one Pb(9) atom. The Pb(10)-Pb(10) bond length is 3.19 Å. The Pb(10)-Pb(2) bond length is 3.13 Å. The Pb(10)-Pb(8) bond length is 3.09 Å. The Pb(10)-Pb(9) bond length is 3.10 Å. In the second Pb site, Pb(11) is bonded in a 8-coordinate geometry to one Rb(1), two equivalent Rb(5), one Pb(5), two equivalent Pb(3), and two equivalent Pb(6) atoms. The Pb(11)-Pb(5) bond length is 3.48 Å. Both Pb(11)-Pb(3) bond lengths are 3.29 Å. Both Pb(11)-Pb(6) bond lengths are 3.09 Å. In the third Pb site, Pb(12) is bonded in a 8-coordinate geometry to one Rb(4), two equivalent Rb(3), one Pb(7), two equivalent Pb(8), and two equivalent Pb(9) atoms. The Pb(12)-Pb(7) bond length is 3.10 Å. Both Pb(12)-Pb(8) bond lengths are 3.13 Å. Both Pb(12)-Pb(9) bond lengths are 3.42 Å. In the fourth Pb site, Pb(1) is bonded in a 8-coordinate geometry to one Rb(2), one Rb(3), one Rb(4), one Rb(5), one Pb(1), one Pb(4), one Pb(5), and one Pb(6) atom. The Pb(1)-Pb(1) bond length is 3.09 Å. The Pb(1)-Pb(4) bond length is 3.11 Å. The Pb(1)-Pb(5) bond length is 3.21 Å. The Pb(1)-Pb(6) bond length is 3.15 Å. In the fifth Pb site, Pb(2) is bonded in a 8-coordinate geometry to one Rb(1), two equivalent Rb(5), one Pb(7), two equivalent Pb(10), and two equivalent Pb(9) atoms. The Pb(2)-Pb(7) bond length is 3.08 Å. Both Pb(2)-Pb(9) bond lengths are 3.49 Å. In the sixth Pb site, Pb(3) is bonded in a 8-coordinate geometry to one Rb(1), one Rb(2), two equivalent Rb(5), one Pb(11), one Pb(3), one Pb(4), and one Pb(6) atom. The Pb(3)-Pb(3) bond length is 3.11 Å. The Pb(3)-Pb(4) bond length is 3.14 Å. The Pb(3)-Pb(6) bond length is 3.12 Å. In the seventh Pb site, Pb(4) is bonded in a distorted body-centered cubic geometry to two equivalent Rb(2), two equivalent Rb(5), two equivalent Pb(1), and two equivalent Pb(3) atoms. In the eighth Pb site, Pb(5) is bonded in a 9-coordinate geometry to two equivalent Rb(2), two equivalent Rb(3), one Pb(11), two equivalent Pb(1), and two equivalent Pb(6) atoms. Both Pb(5)-Pb(6) bond lengths are 3.17 Å. In the ninth Pb site, Pb(6) is bonded in a 7-coordinate geometry to one Rb(2), one Rb(3), one Rb(5), one Pb(1), one Pb(11), one Pb(3), and one Pb(5) atom. In the tenth Pb site, Pb(7) is bonded in a 9-coordinate geometry to one Rb(1), two equivalent Rb(3), two equivalent Rb(5), one Pb(12), one Pb(2), and two equivalent Pb(9) atoms. Both Pb(7)-Pb(9) bond lengths are 3.12 Å. In the eleventh Pb site, Pb(8) is bonded in a 7-coordinate geometry to one Rb(2), one Rb(3), one Rb(4), one Pb(10), one Pb(12), one Pb(8), and one Pb(9) atom. The Pb(8)-Pb(8) bond length is 3.15 Å. The Pb(8)-Pb(9) bond length is 3.16 Å. In the twelfth Pb site, Pb(9) is bonded in a 8-coordinate geometry to one Rb(2), one Rb(3), one Rb(4), one Pb(10), one Pb(12), one Pb(2), one Pb(7), and one Pb(8) atom.