Rb4PbP2Se8 crystallizes in the orthorhombic Ibam space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(3), and six equivalent Se(2) atoms. In the second Rb site, Rb(2) is bonded in a 6-coordinate geometry to two equivalent Se(3) and four equivalent Se(1) atoms. Pb(1) is bonded in a 8-coordinate geometry to four equivalent Se(2) and four equivalent Se(3) atoms. P(1) is bonded in a tetrahedral geometry to one Se(1), one Se(3), and two equivalent Se(2) atoms. There are three inequivalent Se sites. In the first Se site, Se(2) is bonded in a 5-coordinate geometry to three equivalent Rb(1), one Pb(1), and one P(1) atom. In the second Se site, Se(3) is bonded in a 6-coordinate geometry to one Rb(1), two equivalent Rb(2), two equivalent Pb(1), and one P(1) atom. In the third Se site, Se(1) is bonded to one Rb(1), four equivalent Rb(2), and one P(1) atom to form a mixture of distorted corner and edge-sharing SeRb5P octahedra. The corner-sharing octahedral tilt angles range from 1-17°.
Rb4PbP2Se8 crystallizes in the orthorhombic Ibam space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(3), and six equivalent Se(2) atoms. The Rb(1)-Se(1) bond length is 3.67 Å. The Rb(1)-Se(3) bond length is 3.40 Å. There are a spread of Rb(1)-Se(2) bond distances ranging from 3.60-3.72 Å. In the second Rb site, Rb(2) is bonded in a 6-coordinate geometry to two equivalent Se(3) and four equivalent Se(1) atoms. Both Rb(2)-Se(3) bond lengths are 3.69 Å. There are two shorter (3.57 Å) and two longer (3.60 Å) Rb(2)-Se(1) bond lengths. Pb(1) is bonded in a 8-coordinate geometry to four equivalent Se(2) and four equivalent Se(3) atoms. All Pb(1)-Se(2) bond lengths are 3.23 Å. All Pb(1)-Se(3) bond lengths are 3.35 Å. P(1) is bonded in a tetrahedral geometry to one Se(1), one Se(3), and two equivalent Se(2) atoms. The P(1)-Se(1) bond length is 2.22 Å. The P(1)-Se(3) bond length is 2.24 Å. Both P(1)-Se(2) bond lengths are 2.23 Å. There are three inequivalent Se sites. In the first Se site, Se(2) is bonded in a 5-coordinate geometry to three equivalent Rb(1), one Pb(1), and one P(1) atom. In the second Se site, Se(3) is bonded in a 6-coordinate geometry to one Rb(1), two equivalent Rb(2), two equivalent Pb(1), and one P(1) atom. In the third Se site, Se(1) is bonded to one Rb(1), four equivalent Rb(2), and one P(1) atom to form a mixture of distorted corner and edge-sharing SeRb5P octahedra. The corner-sharing octahedral tilt angles range from 1-17°.