Rb4PbO4 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), and three equivalent O(1) atoms. In the second Rb site, Rb(2) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form distorted RbO5 square pyramids that share corners with three equivalent Pb(1)O4 tetrahedra, corners with two equivalent Rb(3)O4 trigonal pyramids,  an edgeedge with one Rb(2)O5 square pyramid,  an edgeedge with one Pb(1)O4 tetrahedra, and  an edgeedge with one Rb(3)O4 trigonal pyramid. In the third Rb site, Rb(3) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form distorted RbO4 trigonal pyramids that share corners with two equivalent Rb(2)O5 square pyramids, corners with four equivalent Pb(1)O4 tetrahedra,  an edgeedge with one Rb(2)O5 square pyramid, and  an edgeedge with one Rb(3)O4 trigonal pyramid. In the fourth Rb site, Rb(4) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(3), and two equivalent O(4) atoms. Pb(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PbO4 tetrahedra that share corners with three equivalent Rb(2)O5 square pyramids, corners with four equivalent Rb(3)O4 trigonal pyramids, and  an edgeedge with one Rb(2)O5 square pyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Rb(2), three equivalent Rb(1), and one Pb(1) atom to form a mixture of distorted corner and edge-sharing ORb5Pb octahedra. The corner-sharing octahedral tilt angles range from 41-46°. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), one Rb(4), and one Pb(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), two equivalent Rb(4), and one Pb(1) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Rb(2), two equivalent Rb(3), two equivalent Rb(4), and one Pb(1) atom.
Rb4PbO4 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), and three equivalent O(1) atoms. The Rb(1)-O(2) bond length is 3.05 Å. The Rb(1)-O(3) bond length is 3.28 Å. There are a spread of Rb(1)-O(1) bond distances ranging from 2.86-3.30 Å. In the second Rb site, Rb(2) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form distorted RbO5 square pyramids that share corners with three equivalent Pb(1)O4 tetrahedra, corners with two equivalent Rb(3)O4 trigonal pyramids,  an edgeedge with one Rb(2)O5 square pyramid,  an edgeedge with one Pb(1)O4 tetrahedra, and  an edgeedge with one Rb(3)O4 trigonal pyramid. The Rb(2)-O(2) bond length is 2.70 Å. The Rb(2)-O(3) bond length is 2.95 Å. The Rb(2)-O(4) bond length is 3.12 Å. There is one shorter (2.68 Å) and one longer (2.93 Å) Rb(2)-O(1) bond length. In the third Rb site, Rb(3) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form distorted RbO4 trigonal pyramids that share corners with two equivalent Rb(2)O5 square pyramids, corners with four equivalent Pb(1)O4 tetrahedra,  an edgeedge with one Rb(2)O5 square pyramid, and  an edgeedge with one Rb(3)O4 trigonal pyramid. The Rb(3)-O(2) bond length is 2.78 Å. The Rb(3)-O(3) bond length is 2.74 Å. There is one shorter (2.73 Å) and one longer (2.77 Å) Rb(3)-O(4) bond length. In the fourth Rb site, Rb(4) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(3), and two equivalent O(4) atoms. The Rb(4)-O(2) bond length is 2.91 Å. There is one shorter (2.95 Å) and one longer (2.96 Å) Rb(4)-O(3) bond length. There is one shorter (2.95 Å) and one longer (3.09 Å) Rb(4)-O(4) bond length. Pb(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PbO4 tetrahedra that share corners with three equivalent Rb(2)O5 square pyramids, corners with four equivalent Rb(3)O4 trigonal pyramids, and  an edgeedge with one Rb(2)O5 square pyramid. The Pb(1)-O(1) bond length is 2.08 Å. The Pb(1)-O(2) bond length is 2.08 Å. The Pb(1)-O(3) bond length is 2.10 Å. The Pb(1)-O(4) bond length is 2.09 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Rb(2), three equivalent Rb(1), and one Pb(1) atom to form a mixture of distorted corner and edge-sharing ORb5Pb octahedra. The corner-sharing octahedral tilt angles range from 41-46°. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), one Rb(4), and one Pb(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), two equivalent Rb(4), and one Pb(1) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Rb(2), two equivalent Rb(3), two equivalent Rb(4), and one Pb(1) atom.