Formation of [(CO2)(n)CH3I](-)anions in the reaction of (CO2)(N)(-) with CH3I

The reactions of negatively charged dusters of carbon dioxide, (CO2)(N)(-) (N greater than or equal to 3), with CH3I were used to form [(CO2)(n)CH3I](-). The observed product distribution showed a distinct bimodal behavior; the mass spectrum of the product anions consisted of [(CO2)(n)CH3I](-) with n = 1-3 and n greater than or equal to 7, while those with n = 4, 5 and 6 were not detected. Photoelectron spectra of the produce anions revealed that [(CO2)(n)CH3I](-) with n = 1-3 possess an anionic core of [(CO2)CH3I](-), while the larger cluster anions (n greater than or equal to 7) have an electronic structure represented as [(CO2)(n)(-) ... CH3I]. The vertical detachment energy of [(CO2)CH2I](-) is estimated to be > 3.25 eV, indicating a delocalization of the excess electron in [(CO2)CH3I](-).