NaCr(CO2)6 crystallizes in the cubic P2_13 space group. Na(1) is bonded in a distorted octahedral geometry to three equivalent O(2) and three equivalent O(4) atoms. All Na(1)-O(2) bond lengths are 2.38 Å. All Na(1)-O(4) bond lengths are 2.40 Å. Cr(1) is bonded in an octahedral geometry to three equivalent O(1) and three equivalent O(3) atoms. All Cr(1)-O(1) bond lengths are 1.97 Å. All Cr(1)-O(3) bond lengths are 1.97 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(2) atom. The C(1)-O(1) bond length is 1.28 Å. The C(1)-O(2) bond length is 1.22 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one O(3) and one O(4) atom. The C(2)-O(3) bond length is 1.28 Å. The C(2)-O(4) bond length is 1.21 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Cr(1) and one C(1) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Na(1) and one C(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Cr(1) and one C(2) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Na(1) and one C(2) atom. Linkers: 12 [O]C(=O)C([O])=O. Metal clusters: 4 [Na] ,4 [Cr]. The MOF has largest included sphere 9.16 A, density 0.55 g/cm3, surface area 3733.84 m2/g, accessible volume 1.42 cm3/g