Diethyl trans-1,2-dicyanoethene-1,2-dicarboxylate at ca 150 K

Abstract

The dimethyl radical anion analogue of (I) has been structurally characterized in its decamethylchromocenium 1:1 adduct, and also as the free ester. One half of the centrosymmetric molecule, necessarily 'trans' about the inversion centre at the mid-point of the central bond, comprises the asymmetric unit of the structure of (I) in space group P21/c. The non-H-atom skeleton of the molecule was close to the planar, despite the highly localized multiple bonds in the cyanide, carbonyl, and olefin components. The bond distances and angles were expected as the asymmetries, about the trigonal C1, and C2 reflecting the electron-pair repulsion effects of the associated double bonds.