Rb3(FeSe2)2 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to two equivalent Se(2) and four equivalent Se(3) atoms to form distorted RbSe6 octahedra that share corners with eight equivalent Fe(1)Se4 tetrahedra, edges with two equivalent Fe(1)Se4 tetrahedra, and faces with two equivalent Rb(1)Se6 octahedra. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to two equivalent Se(1), two equivalent Se(2), and three equivalent Se(3) atoms. Fe(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form FeSe4 tetrahedra that share corners with four equivalent Rb(1)Se6 octahedra,  an edgeedge with one Rb(1)Se6 octahedra, and edges with two equivalent Fe(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 22-63°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to four equivalent Rb(2) and two equivalent Fe(1) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to two equivalent Rb(1), four equivalent Rb(2), and two equivalent Fe(1) atoms. In the third Se site, Se(3) is bonded in a 7-coordinate geometry to two equivalent Rb(1), three equivalent Rb(2), and two equivalent Fe(1) atoms.
Rb3(FeSe2)2 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to two equivalent Se(2) and four equivalent Se(3) atoms to form distorted RbSe6 octahedra that share corners with eight equivalent Fe(1)Se4 tetrahedra, edges with two equivalent Fe(1)Se4 tetrahedra, and faces with two equivalent Rb(1)Se6 octahedra. There is one shorter (3.38 Å) and one longer (3.39 Å) Rb(1)-Se(2) bond length. There are two shorter (3.42 Å) and two longer (3.53 Å) Rb(1)-Se(3) bond lengths. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to two equivalent Se(1), two equivalent Se(2), and three equivalent Se(3) atoms. There is one shorter (3.38 Å) and one longer (3.49 Å) Rb(2)-Se(1) bond length. There is one shorter (3.67 Å) and one longer (4.02 Å) Rb(2)-Se(2) bond length. There are a spread of Rb(2)-Se(3) bond distances ranging from 3.58-3.72 Å. Fe(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form FeSe4 tetrahedra that share corners with four equivalent Rb(1)Se6 octahedra,  an edgeedge with one Rb(1)Se6 octahedra, and edges with two equivalent Fe(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 22-63°. The Fe(1)-Se(1) bond length is 2.42 Å. The Fe(1)-Se(2) bond length is 2.45 Å. There is one shorter (2.46 Å) and one longer (2.49 Å) Fe(1)-Se(3) bond length. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to four equivalent Rb(2) and two equivalent Fe(1) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to two equivalent Rb(1), four equivalent Rb(2), and two equivalent Fe(1) atoms. In the third Se site, Se(3) is bonded in a 7-coordinate geometry to two equivalent Rb(1), three equivalent Rb(2), and two equivalent Fe(1) atoms.