Negative Ion Photoelectron Spectroscopy of NH2-(NH3)1 and NH2-(NH3)2: Gas Phase Basicities of Partially Solvated Anions

The photoelectron spectra of the gas phase negative cluster ions NH2-(NH3)1 and NH2-(NH3)2 are reported. The spectra imply that these ions consist of intact amide ions solvated by ammonia. Vertical detachment energies and ion-solvent dissociation energies are obtained. In addition, spectral features are also observed that indicate that the ammonia moiety in these cluster anions is distorted from the equilibrium configuration of the free ammonia molecule. The spectra are compared to the photoelectron spectra of H-(NH~)I and H-(NH3)2. Gas phase basicities are determined for NH~-(NH~)I, NH-(NH3)2, H-(NH3),, and H-(NH3)2. While NH2- is a stronger base than H- in the gas phase, our data show that the addition of only two ammonia