K4Pb9 is Magnesium tetraboride-like structured and crystallizes in the monoclinic P2_1/m space group. There are five inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one Pb(1), one Pb(10), one Pb(11), one Pb(3), one Pb(4), one Pb(6), one Pb(8), and one Pb(9) atom. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Pb(2), two equivalent Pb(10), two equivalent Pb(6), and two equivalent Pb(9) atoms. In the third K site, K(3) is bonded in a 8-coordinate geometry to one Pb(1), one Pb(10), one Pb(2), one Pb(3), one Pb(6), one Pb(7), one Pb(8), and one Pb(9) atom. In the fourth K site, K(4) is bonded in a 8-coordinate geometry to one Pb(11), one Pb(12), one Pb(5), one Pb(6), one Pb(7), one Pb(8), and two equivalent Pb(4) atoms. In the fifth K site, K(5) is bonded in a 7-coordinate geometry to one Pb(12), one Pb(5), one Pb(7), two equivalent Pb(4), and two equivalent Pb(9) atoms. There are twelve inequivalent Pb sites. In the first Pb site, Pb(11) is bonded in a distorted body-centered cubic geometry to two equivalent K(1), two equivalent K(4), two equivalent Pb(4), and two equivalent Pb(6) atoms. In the second Pb site, Pb(12) is bonded in a 8-coordinate geometry to one K(5), two equivalent K(4), one Pb(1), two equivalent Pb(4), and two equivalent Pb(8) atoms. In the third Pb site, Pb(1) is bonded in a 9-coordinate geometry to two equivalent K(1), two equivalent K(3), one Pb(12), two equivalent Pb(6), and two equivalent Pb(8) atoms. In the fourth Pb site, Pb(2) is bonded in a 8-coordinate geometry to one K(2), two equivalent K(3), one Pb(7), two equivalent Pb(10), and two equivalent Pb(3) atoms. In the fifth Pb site, Pb(3) is bonded in a 1-coordinate geometry to one K(1), one K(3), one Pb(10), one Pb(2), one Pb(7), and one Pb(9) atom. In the sixth Pb site, Pb(4) is bonded in a 8-coordinate geometry to one K(1), one K(5), two equivalent K(4), one Pb(11), one Pb(12), one Pb(4), and one Pb(8) atom. In the seventh Pb site, Pb(5) is bonded in a 6-coordinate geometry to one K(5), two equivalent K(4), one Pb(7), and two equivalent Pb(9) atoms. In the eighth Pb site, Pb(6) is bonded in a 8-coordinate geometry to one K(1), one K(2), one K(3), one K(4), one Pb(1), one Pb(11), one Pb(6), and one Pb(8) atom. In the ninth Pb site, Pb(7) is bonded in a 9-coordinate geometry to one K(5), two equivalent K(3), two equivalent K(4), one Pb(2), one Pb(5), and two equivalent Pb(3) atoms. In the tenth Pb site, Pb(8) is bonded in a 7-coordinate geometry to one K(1), one K(3), one K(4), one Pb(1), one Pb(12), one Pb(4), and one Pb(6) atom. In the eleventh Pb site, Pb(9) is bonded in a 8-coordinate geometry to one K(1), one K(2), one K(3), one K(5), one Pb(10), one Pb(3), one Pb(5), and one Pb(9) atom. In the twelfth Pb site, Pb(10) is bonded in a 7-coordinate geometry to one K(1), one K(2), one K(3), one Pb(10), one Pb(2), one Pb(3), and one Pb(9) atom.
K4Pb9 is Magnesium tetraboride-like structured and crystallizes in the monoclinic P2_1/m space group. There are five inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one Pb(1), one Pb(10), one Pb(11), one Pb(3), one Pb(4), one Pb(6), one Pb(8), and one Pb(9) atom. The K(1)-Pb(1) bond length is 4.04 Å. The K(1)-Pb(10) bond length is 3.89 Å. The K(1)-Pb(11) bond length is 3.98 Å. The K(1)-Pb(3) bond length is 4.00 Å. The K(1)-Pb(4) bond length is 4.06 Å. The K(1)-Pb(6) bond length is 3.85 Å. The K(1)-Pb(8) bond length is 3.71 Å. The K(1)-Pb(9) bond length is 3.82 Å. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Pb(2), two equivalent Pb(10), two equivalent Pb(6), and two equivalent Pb(9) atoms. The K(2)-Pb(2) bond length is 3.75 Å. Both K(2)-Pb(10) bond lengths are 3.86 Å. Both K(2)-Pb(6) bond lengths are 3.87 Å. Both K(2)-Pb(9) bond lengths are 3.90 Å. In the third K site, K(3) is bonded in a 8-coordinate geometry to one Pb(1), one Pb(10), one Pb(2), one Pb(3), one Pb(6), one Pb(7), one Pb(8), and one Pb(9) atom. The K(3)-Pb(1) bond length is 3.97 Å. The K(3)-Pb(10) bond length is 3.73 Å. The K(3)-Pb(2) bond length is 3.94 Å. The K(3)-Pb(3) bond length is 3.66 Å. The K(3)-Pb(6) bond length is 3.76 Å. The K(3)-Pb(7) bond length is 3.99 Å. The K(3)-Pb(8) bond length is 4.01 Å. The K(3)-Pb(9) bond length is 3.66 Å. In the fourth K site, K(4) is bonded in a 8-coordinate geometry to one Pb(11), one Pb(12), one Pb(5), one Pb(6), one Pb(7), one Pb(8), and two equivalent Pb(4) atoms. The K(4)-Pb(11) bond length is 3.70 Å. The K(4)-Pb(12) bond length is 4.09 Å. The K(4)-Pb(5) bond length is 3.84 Å. The K(4)-Pb(6) bond length is 3.72 Å. The K(4)-Pb(7) bond length is 4.05 Å. The K(4)-Pb(8) bond length is 3.74 Å. There is one shorter (3.82 Å) and one longer (4.13 Å) K(4)-Pb(4) bond length. In the fifth K site, K(5) is bonded in a 7-coordinate geometry to one Pb(12), one Pb(5), one Pb(7), two equivalent Pb(4), and two equivalent Pb(9) atoms. The K(5)-Pb(12) bond length is 3.77 Å. The K(5)-Pb(5) bond length is 3.73 Å. The K(5)-Pb(7) bond length is 3.59 Å. Both K(5)-Pb(4) bond lengths are 3.72 Å. Both K(5)-Pb(9) bond lengths are 3.78 Å. There are twelve inequivalent Pb sites. In the first Pb site, Pb(11) is bonded in a distorted body-centered cubic geometry to two equivalent K(1), two equivalent K(4), two equivalent Pb(4), and two equivalent Pb(6) atoms. Both Pb(11)-Pb(4) bond lengths are 3.20 Å. Both Pb(11)-Pb(6) bond lengths are 3.17 Å. In the second Pb site, Pb(12) is bonded in a 8-coordinate geometry to one K(5), two equivalent K(4), one Pb(1), two equivalent Pb(4), and two equivalent Pb(8) atoms. The Pb(12)-Pb(1) bond length is 3.52 Å. Both Pb(12)-Pb(4) bond lengths are 3.39 Å. Both Pb(12)-Pb(8) bond lengths are 3.15 Å. In the third Pb site, Pb(1) is bonded in a 9-coordinate geometry to two equivalent K(1), two equivalent K(3), one Pb(12), two equivalent Pb(6), and two equivalent Pb(8) atoms. Both Pb(1)-Pb(6) bond lengths are 3.28 Å. Both Pb(1)-Pb(8) bond lengths are 3.26 Å. In the fourth Pb site, Pb(2) is bonded in a 8-coordinate geometry to one K(2), two equivalent K(3), one Pb(7), two equivalent Pb(10), and two equivalent Pb(3) atoms. The Pb(2)-Pb(7) bond length is 3.15 Å. Both Pb(2)-Pb(10) bond lengths are 3.21 Å. Both Pb(2)-Pb(3) bond lengths are 3.48 Å. In the fifth Pb site, Pb(3) is bonded in a 1-coordinate geometry to one K(1), one K(3), one Pb(10), one Pb(2), one Pb(7), and one Pb(9) atom. The Pb(3)-Pb(10) bond length is 3.23 Å. The Pb(3)-Pb(7) bond length is 3.19 Å. The Pb(3)-Pb(9) bond length is 3.16 Å. In the sixth Pb site, Pb(4) is bonded in a 8-coordinate geometry to one K(1), one K(5), two equivalent K(4), one Pb(11), one Pb(12), one Pb(4), and one Pb(8) atom. The Pb(4)-Pb(4) bond length is 3.18 Å. The Pb(4)-Pb(8) bond length is 3.19 Å. In the seventh Pb site, Pb(5) is bonded in a 6-coordinate geometry to one K(5), two equivalent K(4), one Pb(7), and two equivalent Pb(9) atoms. The Pb(5)-Pb(7) bond length is 3.14 Å. Both Pb(5)-Pb(9) bond lengths are 3.20 Å. In the eighth Pb site, Pb(6) is bonded in a 8-coordinate geometry to one K(1), one K(2), one K(3), one K(4), one Pb(1), one Pb(11), one Pb(6), and one Pb(8) atom. The Pb(6)-Pb(6) bond length is 3.16 Å. The Pb(6)-Pb(8) bond length is 3.21 Å. In the ninth Pb site, Pb(7) is bonded in a 9-coordinate geometry to one K(5), two equivalent K(3), two equivalent K(4), one Pb(2), one Pb(5), and two equivalent Pb(3) atoms. In the tenth Pb site, Pb(8) is bonded in a 7-coordinate geometry to one K(1), one K(3), one K(4), one Pb(1), one Pb(12), one Pb(4), and one Pb(6) atom. In the eleventh Pb site, Pb(9) is bonded in a 8-coordinate geometry to one K(1), one K(2), one K(3), one K(5), one Pb(10), one Pb(3), one Pb(5), and one Pb(9) atom. The Pb(9)-Pb(10) bond length is 3.16 Å. The Pb(9)-Pb(9) bond length is 3.23 Å. In the twelfth Pb site, Pb(10) is bonded in a 7-coordinate geometry to one K(1), one K(2), one K(3), one Pb(10), one Pb(2), one Pb(3), and one Pb(9) atom. The Pb(10)-Pb(10) bond length is 3.20 Å.