Rb2Be2Si2O7 crystallizes in the orthorhombic Pnn2 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 10-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(4), and four equivalent O(1) atoms. In the second Rb site, Rb(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Be(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing SiO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Rb(2), two equivalent Rb(1), one Be(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Rb(2), one Be(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Rb(2), one Be(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to two equivalent Rb(1) and two equivalent Si(1) atoms.
Rb2Be2Si2O7 crystallizes in the orthorhombic Pnn2 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 10-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(4), and four equivalent O(1) atoms. Both Rb(1)-O(2) bond lengths are 3.16 Å. Both Rb(1)-O(3) bond lengths are 2.91 Å. Both Rb(1)-O(4) bond lengths are 3.10 Å. There are two shorter (3.33 Å) and two longer (3.38 Å) Rb(1)-O(1) bond lengths. In the second Rb site, Rb(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Both Rb(2)-O(1) bond lengths are 2.95 Å. Both Rb(2)-O(2) bond lengths are 2.98 Å. Both Rb(2)-O(3) bond lengths are 3.21 Å. Be(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. The Be(1)-O(1) bond length is 1.54 Å. The Be(1)-O(2) bond length is 1.54 Å. The Be(1)-O(3) bond length is 1.54 Å. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing SiO4 tetrahedra. The Si(1)-O(1) bond length is 1.63 Å. The Si(1)-O(2) bond length is 1.63 Å. The Si(1)-O(3) bond length is 1.63 Å. The Si(1)-O(4) bond length is 1.66 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Rb(2), two equivalent Rb(1), one Be(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Rb(2), one Be(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Rb(2), one Be(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to two equivalent Rb(1) and two equivalent Si(1) atoms.