The influence of electron-withdrawing substituents on the geometries and barriers to inversion of vinyl anions

Whereas $\text{ab}$$\text{initio}$ calculations predict that the vinyl anion is bent and has a high barrier to inversion, substitution of cyano, methoxycarbonyl, and formyl substituents at C-1 lower this barrier. Nevertheless, the first two substituents produce significantly bent anions, while the bent and linear 1-formylvinyl anions are essentially isoenergetic.