Crystal structure of the inverse crown ether tetra­kis­[μ(2)-bis­(tri­methyl­sil­yl)amido]-μ(4)-oxido-dicobalt(II)disodium, [Co(2)Na(2){μ(2)-N(SiMe(3))(2)}(4)](μ(4)-O)

The title compound, [Co(2)Na(2){μ(2)-N(SiMe(3))(2)}(4)](μ(4)-O), (I), represents a new entry in the class of inverse crown ethers. In the mol­ecule, each Co atom is formally in the oxidation state +II. The structure contains one half of a unique mol­ecule per asymmetric unit with the central μ(4)-oxido ligand residing on an inversion center, leading to a planar coordination to the Na and Co atoms. In the crystal, bulky tri­methyl­silyl substituents prevent additional inter­actions with cobalt. However, weak inter­molecular Na⋯H(3)C—Si inter­actions form an infinite chain along [010]. The structure is isotypic with its Mg, Mn and Zn analogues.