Na2CuC2H6O9 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(5), one O(7), one O(9), and two equivalent O(3) atoms to form a mixture of distorted face, edge, and corner-sharing NaO6 octahedra. The corner-sharing octahedral tilt angles are 77°. The Na(1)-O(1) bond length is 2.35 Å. The Na(1)-O(5) bond length is 2.47 Å. The Na(1)-O(7) bond length is 2.40 Å. The Na(1)-O(9) bond length is 2.36 Å. There is one shorter (2.36 Å) and one longer (2.43 Å) Na(1)-O(3) bond length. In the second Na site, Na(2) is bonded to one O(1), one O(3), one O(5), one O(9), and two equivalent O(8) atoms to form a mixture of face and edge-sharing NaO6 octahedra. The Na(2)-O(1) bond length is 2.44 Å. The Na(2)-O(3) bond length is 2.42 Å. The Na(2)-O(5) bond length is 2.43 Å. The Na(2)-O(9) bond length is 2.36 Å. There is one shorter (2.33 Å) and one longer (2.45 Å) Na(2)-O(8) bond length. Cu(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(6), and one O(7) atom. The Cu(1)-O(1) bond length is 2.01 Å. The Cu(1)-O(2) bond length is 2.06 Å. The Cu(1)-O(4) bond length is 1.98 Å. The Cu(1)-O(6) bond length is 1.99 Å. The Cu(1)-O(7) bond length is 2.34 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. The C(1)-O(1) bond length is 1.31 Å. The C(1)-O(2) bond length is 1.32 Å. The C(1)-O(3) bond length is 1.26 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(4), one O(5), and one O(6) atom. The C(2)-O(4) bond length is 1.30 Å. The C(2)-O(5) bond length is 1.27 Å. The C(2)-O(6) bond length is 1.32 Å. There are six inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(7) atom. The H(1)-O(7) bond length is 0.99 Å. In the second H site, H(2) is bonded in a distorted single-bond geometry to one O(2) and one O(7) atom. The H(2)-O(2) bond length is 1.71 Å. The H(2)-O(7) bond length is 0.99 Å. In the third H site, H(3) is bonded in a distorted single-bond geometry to one O(6) and one O(8) atom. The H(3)-O(6) bond length is 1.70 Å. The H(3)-O(8) bond length is 1.00 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(8) atom. The H(4)-O(8) bond length is 0.98 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(9) atom. The H(5)-O(9) bond length is 0.99 Å. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(5) and one O(9) atom. The H(6)-O(5) bond length is 1.70 Å. The H(6)-O(9) bond length is 1.00 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Cu(1), and one C(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Cu(1), one C(1), and one H(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one C(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Cu(1) and one C(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one C(2), and one H(6) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Cu(1), one C(2), and one H(3) atom. In the seventh O site, O(7) is bonded in a distorted water-like geometry to one Na(1), one Cu(1), one H(1), and one H(2) atom. In the eighth O site, O(8) is bonded in a distorted water-like geometry to two equivalent Na(2), one H(3), and one H(4) atom. In the ninth O site, O(9) is bonded in a distorted water-like geometry to one Na(1), one Na(2), one H(5), and one H(6) atom. Linkers: 8 [O]C([O])=O ,12 O. Metal clusters: 8 [Na] ,4 [Cu]. The MOF has largest included sphere 1.61 A, density 2.32 g/cm3, surface area 2043.45 m2/g, accessible volume 0.06 cm3/g