RbFeSe2 crystallizes in the monoclinic C2/c space group. Rb(1) is bonded to eight equivalent Se(1) atoms to form distorted RbSe8 hexagonal bipyramids that share corners with four equivalent Rb(1)Se8 hexagonal bipyramids, corners with six equivalent Fe(1)Se4 tetrahedra, edges with six equivalent Rb(1)Se8 hexagonal bipyramids, edges with five equivalent Fe(1)Se4 tetrahedra, and faces with two equivalent Rb(1)Se8 hexagonal bipyramids. Fe(1) is bonded to four equivalent Se(1) atoms to form FeSe4 tetrahedra that share corners with six equivalent Rb(1)Se8 hexagonal bipyramids, edges with five equivalent Rb(1)Se8 hexagonal bipyramids, and edges with two equivalent Fe(1)Se4 tetrahedra. Se(1) is bonded in a 6-coordinate geometry to four equivalent Rb(1) and two equivalent Fe(1) atoms.
RbFeSe2 crystallizes in the monoclinic C2/c space group. Rb(1) is bonded to eight equivalent Se(1) atoms to form distorted RbSe8 hexagonal bipyramids that share corners with four equivalent Rb(1)Se8 hexagonal bipyramids, corners with six equivalent Fe(1)Se4 tetrahedra, edges with six equivalent Rb(1)Se8 hexagonal bipyramids, edges with five equivalent Fe(1)Se4 tetrahedra, and faces with two equivalent Rb(1)Se8 hexagonal bipyramids. There are six shorter (3.55 Å) and two longer (3.67 Å) Rb(1)-Se(1) bond lengths. Fe(1) is bonded to four equivalent Se(1) atoms to form FeSe4 tetrahedra that share corners with six equivalent Rb(1)Se8 hexagonal bipyramids, edges with five equivalent Rb(1)Se8 hexagonal bipyramids, and edges with two equivalent Fe(1)Se4 tetrahedra. There are two shorter (2.34 Å) and two longer (2.35 Å) Fe(1)-Se(1) bond lengths. Se(1) is bonded in a 6-coordinate geometry to four equivalent Rb(1) and two equivalent Fe(1) atoms.