Synthesis and crystal structure of tetra-methyl ()-4,4'-(ethene-1,2-di-yl)bis-(5-nitro-benzene-1,2-di-carboxyl-ate).

The title compound, CHNO, was obtained as a by-product during the planned synthesis of 1,2-bis-(2-nitro-4,5-dimethyl phthalate)ethane by oxidative dimerization starting from dimethyl-4-methyl-5-nitro phthalate. To identify this compound unambiguously, a single-crystal structure analysis was performed. The asymmetric unit consists of half a mol-ecule that is located at a centre of inversion.