Microsolvation of the Dicyanamide Anion: [N(CN)2-](H2O)n (n = 0−12)

Photoelectron spectroscopy is combined with ab initio calculations to study the microsolvation of the dicyanamide anion, N(CN)2-. Photoelectron spectra of [N(CN)2-](H2O)n (n = 0−12) have been measured at room temperature and also at low temperature for n = 0−4. Vibrationally resolved photoelectron spectra are obtained for N(CN)2-, allowing the electron affinity of the N(CN)2 radical to be determined accurately as 4.135 ± 0.010 eV. The electron binding energies and the spectral width of the hydrated clusters are observed to increase with the number of water molecules. The first five waters are observed to provide significant stabilization to the solute, whereas the stabilization becomes weaker for n > 5. The spectral width, which carries information about the solvent reorganization upon electron detachment in [N(CN)2-](H2O)n, levels off for n > 6. Theoretical calculations reveal several close-lying isomers for n = 1 and 2 due to the fact that the N(CN)2- anion possesses three almost equivalent hydration sites. In all the hydrated clusters, the most stable structures consist of a water cluster solvating one end of the N(CN)2- anion.