Ionicity in Anionic Photoexcited States. The Effect of the Covalent Character of the Carbon-Metal Bond on the Photochemical Ring Opening of Cyclopropyl Anions

Article abstract of DOI:10.1021/jo00151a009

Although 1-cyano- and 1-carbomethoxy-substituted trans-2,3-diphenylcyclopropyllithiums ring open to the corresponding allyllithiums upon photoexcitation, the analogous 1-vinyl- and 1-bromo-substituted cyclopropyllithiums do not.Shifts of the oxidative peak potential in the cyclic voltammetric scans of the photoreactive cyclopropyllithiums imply that they exist as ion pairs at low temperature in THF solution.The importance of the ionic character of the carbon-metal bond in determining the efficiency of photorearrangement is also implied by MNDO reaction path calculations.