Rb2CuC2O7 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 9-coordinate geometry to one O(2), one O(6), two equivalent O(1), two equivalent O(5), and three equivalent O(7) atoms. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one O(3), one O(4), one O(7), two equivalent O(1), and two equivalent O(2) atoms. Cu(1) is bonded to one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted corner-sharing CuO5 square pyramids. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(2), one O(3), and one O(4) atom. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(5), one O(6), and one O(7) atom. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Cu(1), and one C(1) atom. In the second O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent Rb(1), one Cu(1), and one C(2) atom. In the third O site, O(6) is bonded in a distorted water-like geometry to one Rb(1), one Cu(1), and one C(2) atom. In the fourth O site, O(7) is bonded in a distorted single-bond geometry to one Rb(2), three equivalent Rb(1), and one C(2) atom. In the fifth O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Rb(1) and two equivalent Rb(2) atoms. In the sixth O site, O(2) is bonded in a distorted single-bond geometry to one Rb(1), two equivalent Rb(2), and one C(1) atom. In the seventh O site, O(3) is bonded in a distorted L-shaped geometry to one Rb(2), one Cu(1), and one C(1) atom.
Rb2CuC2O7 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 9-coordinate geometry to one O(2), one O(6), two equivalent O(1), two equivalent O(5), and three equivalent O(7) atoms. The Rb(1)-O(2) bond length is 3.00 Å. The Rb(1)-O(6) bond length is 3.09 Å. There is one shorter (2.93 Å) and one longer (3.22 Å) Rb(1)-O(1) bond length. There is one shorter (3.07 Å) and one longer (3.22 Å) Rb(1)-O(5) bond length. There are a spread of Rb(1)-O(7) bond distances ranging from 2.93-3.43 Å. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one O(3), one O(4), one O(7), two equivalent O(1), and two equivalent O(2) atoms. The Rb(2)-O(3) bond length is 3.02 Å. The Rb(2)-O(4) bond length is 2.98 Å. The Rb(2)-O(7) bond length is 2.96 Å. There is one shorter (3.04 Å) and one longer (3.05 Å) Rb(2)-O(1) bond length. There is one shorter (2.92 Å) and one longer (3.03 Å) Rb(2)-O(2) bond length. Cu(1) is bonded to one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted corner-sharing CuO5 square pyramids. The Cu(1)-O(3) bond length is 1.94 Å. The Cu(1)-O(5) bond length is 1.94 Å. The Cu(1)-O(6) bond length is 1.92 Å. There is one shorter (1.98 Å) and one longer (2.47 Å) Cu(1)-O(4) bond length. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(2), one O(3), and one O(4) atom. The C(1)-O(2) bond length is 1.25 Å. The C(1)-O(3) bond length is 1.33 Å. The C(1)-O(4) bond length is 1.33 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(5), one O(6), and one O(7) atom. The C(2)-O(5) bond length is 1.32 Å. The C(2)-O(6) bond length is 1.32 Å. The C(2)-O(7) bond length is 1.26 Å. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Cu(1), and one C(1) atom. In the second O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent Rb(1), one Cu(1), and one C(2) atom. In the third O site, O(6) is bonded in a distorted water-like geometry to one Rb(1), one Cu(1), and one C(2) atom. In the fourth O site, O(7) is bonded in a distorted single-bond geometry to one Rb(2), three equivalent Rb(1), and one C(2) atom. In the fifth O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Rb(1) and two equivalent Rb(2) atoms. In the sixth O site, O(2) is bonded in a distorted single-bond geometry to one Rb(1), two equivalent Rb(2), and one C(1) atom. In the seventh O site, O(3) is bonded in a distorted L-shaped geometry to one Rb(2), one Cu(1), and one C(1) atom.