Rb2Se5 crystallizes in the orthorhombic P2_12_12_1 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 10-coordinate geometry to one Se(3), two equivalent Se(1), two equivalent Se(2), two equivalent Se(4), and three equivalent Se(5) atoms. In the second Rb site, Rb(2) is bonded in a 9-coordinate geometry to one Se(2), two equivalent Se(4), two equivalent Se(5), and four equivalent Se(1) atoms. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a 7-coordinate geometry to two equivalent Rb(1), four equivalent Rb(2), and one Se(2) atom. In the second Se site, Se(2) is bonded in a distorted pentagonal planar geometry to one Rb(2), two equivalent Rb(1), one Se(1), and one Se(3) atom. In the third Se site, Se(3) is bonded in a distorted trigonal planar geometry to one Rb(1), one Se(2), and one Se(4) atom. In the fourth Se site, Se(4) is bonded in a 6-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), one Se(3), and one Se(5) atom. In the fifth Se site, Se(5) is bonded to two equivalent Rb(2), three equivalent Rb(1), and one Se(4) atom to form a mixture of distorted corner and edge-sharing SeRb5Se octahedra. The corner-sharing octahedral tilt angles range from 5-41°.
Rb2Se5 crystallizes in the orthorhombic P2_12_12_1 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 10-coordinate geometry to one Se(3), two equivalent Se(1), two equivalent Se(2), two equivalent Se(4), and three equivalent Se(5) atoms. The Rb(1)-Se(3) bond length is 3.74 Å. There is one shorter (3.62 Å) and one longer (3.78 Å) Rb(1)-Se(1) bond length. There is one shorter (3.54 Å) and one longer (3.71 Å) Rb(1)-Se(2) bond length. There is one shorter (3.73 Å) and one longer (3.74 Å) Rb(1)-Se(4) bond length. There are a spread of Rb(1)-Se(5) bond distances ranging from 3.44-3.64 Å. In the second Rb site, Rb(2) is bonded in a 9-coordinate geometry to one Se(2), two equivalent Se(4), two equivalent Se(5), and four equivalent Se(1) atoms. The Rb(2)-Se(2) bond length is 3.64 Å. There is one shorter (3.66 Å) and one longer (3.67 Å) Rb(2)-Se(4) bond length. There is one shorter (3.60 Å) and one longer (3.73 Å) Rb(2)-Se(5) bond length. There are a spread of Rb(2)-Se(1) bond distances ranging from 3.58-3.85 Å. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a 7-coordinate geometry to two equivalent Rb(1), four equivalent Rb(2), and one Se(2) atom. The Se(1)-Se(2) bond length is 2.34 Å. In the second Se site, Se(2) is bonded in a distorted pentagonal planar geometry to one Rb(2), two equivalent Rb(1), one Se(1), and one Se(3) atom. The Se(2)-Se(3) bond length is 2.37 Å. In the third Se site, Se(3) is bonded in a distorted trigonal planar geometry to one Rb(1), one Se(2), and one Se(4) atom. The Se(3)-Se(4) bond length is 2.39 Å. In the fourth Se site, Se(4) is bonded in a 6-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), one Se(3), and one Se(5) atom. The Se(4)-Se(5) bond length is 2.35 Å. In the fifth Se site, Se(5) is bonded to two equivalent Rb(2), three equivalent Rb(1), and one Se(4) atom to form a mixture of distorted corner and edge-sharing SeRb5Se octahedra. The corner-sharing octahedral tilt angles range from 5-41°.