Rb2Cr2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(3), one O(4), one O(6), one O(7), two equivalent O(1), and two equivalent O(2) atoms. In the second Rb site, Rb(2) is bonded in a 9-coordinate geometry to one O(1), one O(2), one O(3), two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form corner-sharing CrO4 tetrahedra. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Rb(2), two equivalent Rb(1), and one Cr(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Rb(2), two equivalent Rb(1), and one Cr(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), and one Cr(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Rb(1), one Cr(1), and one Cr(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Rb(2) and one Cr(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Rb(1), two equivalent Rb(2), and one Cr(1) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Rb(1), two equivalent Rb(2), and one Cr(1) atom.
Rb2Cr2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(3), one O(4), one O(6), one O(7), two equivalent O(1), and two equivalent O(2) atoms. The Rb(1)-O(3) bond length is 2.87 Å. The Rb(1)-O(4) bond length is 3.12 Å. The Rb(1)-O(6) bond length is 2.90 Å. The Rb(1)-O(7) bond length is 2.89 Å. There is one shorter (3.08 Å) and one longer (3.10 Å) Rb(1)-O(1) bond length. There is one shorter (2.93 Å) and one longer (2.96 Å) Rb(1)-O(2) bond length. In the second Rb site, Rb(2) is bonded in a 9-coordinate geometry to one O(1), one O(2), one O(3), two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms. The Rb(2)-O(1) bond length is 3.01 Å. The Rb(2)-O(2) bond length is 2.93 Å. The Rb(2)-O(3) bond length is 2.86 Å. There is one shorter (2.94 Å) and one longer (3.34 Å) Rb(2)-O(5) bond length. There is one shorter (2.90 Å) and one longer (2.93 Å) Rb(2)-O(6) bond length. There is one shorter (3.02 Å) and one longer (3.04 Å) Rb(2)-O(7) bond length. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form corner-sharing CrO4 tetrahedra. The Cr(1)-O(4) bond length is 1.78 Å. The Cr(1)-O(5) bond length is 1.61 Å. The Cr(1)-O(6) bond length is 1.62 Å. The Cr(1)-O(7) bond length is 1.62 Å. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. The Cr(2)-O(1) bond length is 1.62 Å. The Cr(2)-O(2) bond length is 1.62 Å. The Cr(2)-O(3) bond length is 1.61 Å. The Cr(2)-O(4) bond length is 1.77 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Rb(2), two equivalent Rb(1), and one Cr(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Rb(2), two equivalent Rb(1), and one Cr(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), and one Cr(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Rb(1), one Cr(1), and one Cr(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Rb(2) and one Cr(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Rb(1), two equivalent Rb(2), and one Cr(1) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Rb(1), two equivalent Rb(2), and one Cr(1) atom.