Rb2GeSe3 crystallizes in the monoclinic C2/m space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 5-coordinate geometry to two equivalent Se(3) and three equivalent Se(1) atoms. In the second Rb site, Rb(2) is bonded to two equivalent Se(1), two equivalent Se(2), and three equivalent Se(3) atoms to form distorted RbSe7 pentagonal bipyramids that share corners with two equivalent Rb(2)Se7 pentagonal bipyramids, corners with three equivalent Ge(1)Se4 tetrahedra, edges with four equivalent Rb(2)Se7 pentagonal bipyramids, and edges with three equivalent Ge(1)Se4 tetrahedra. Ge(1) is bonded to one Se(1), one Se(3), and two equivalent Se(2) atoms to form GeSe4 tetrahedra that share corners with three equivalent Rb(2)Se7 pentagonal bipyramids, edges with three equivalent Rb(2)Se7 pentagonal bipyramids, and  an edgeedge with one Ge(1)Se4 tetrahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Rb(2), three equivalent Rb(1), and one Ge(1) atom to form a mixture of distorted corner and edge-sharing SeRb5Ge octahedra. The corner-sharing octahedral tilt angles range from 8-70°. In the second Se site, Se(2) is bonded in a 2-coordinate geometry to two equivalent Rb(2) and two equivalent Ge(1) atoms. In the third Se site, Se(3) is bonded to two equivalent Rb(1), three equivalent Rb(2), and one Ge(1) atom to form a mixture of distorted corner and edge-sharing SeRb5Ge octahedra. The corner-sharing octahedral tilt angles range from 8-70°.
Rb2GeSe3 crystallizes in the monoclinic C2/m space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 5-coordinate geometry to two equivalent Se(3) and three equivalent Se(1) atoms. There is one shorter (3.48 Å) and one longer (3.65 Å) Rb(1)-Se(3) bond length. There is one shorter (3.46 Å) and two longer (3.65 Å) Rb(1)-Se(1) bond lengths. In the second Rb site, Rb(2) is bonded to two equivalent Se(1), two equivalent Se(2), and three equivalent Se(3) atoms to form distorted RbSe7 pentagonal bipyramids that share corners with two equivalent Rb(2)Se7 pentagonal bipyramids, corners with three equivalent Ge(1)Se4 tetrahedra, edges with four equivalent Rb(2)Se7 pentagonal bipyramids, and edges with three equivalent Ge(1)Se4 tetrahedra. There is one shorter (3.43 Å) and one longer (3.44 Å) Rb(2)-Se(1) bond length. Both Rb(2)-Se(2) bond lengths are 3.69 Å. There is one shorter (3.47 Å) and two longer (3.62 Å) Rb(2)-Se(3) bond lengths. Ge(1) is bonded to one Se(1), one Se(3), and two equivalent Se(2) atoms to form GeSe4 tetrahedra that share corners with three equivalent Rb(2)Se7 pentagonal bipyramids, edges with three equivalent Rb(2)Se7 pentagonal bipyramids, and  an edgeedge with one Ge(1)Se4 tetrahedra. The Ge(1)-Se(1) bond length is 2.31 Å. The Ge(1)-Se(3) bond length is 2.30 Å. Both Ge(1)-Se(2) bond lengths are 2.44 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Rb(2), three equivalent Rb(1), and one Ge(1) atom to form a mixture of distorted corner and edge-sharing SeRb5Ge octahedra. The corner-sharing octahedral tilt angles range from 8-70°. In the second Se site, Se(2) is bonded in a 2-coordinate geometry to two equivalent Rb(2) and two equivalent Ge(1) atoms. In the third Se site, Se(3) is bonded to two equivalent Rb(1), three equivalent Rb(2), and one Ge(1) atom to form a mixture of distorted corner and edge-sharing SeRb5Ge octahedra. The corner-sharing octahedral tilt angles range from 8-70°.