THE POSSIBILITY OF THE EXISTENCE OF (H2O)(N)(-) ANIONS WITH N=5,6

Structural changes that occur in cyclic and chain-like water pentamers and hexamers when an electron is added wen analysed at the unrestrict ed Hartree-Fock level. The vertical and adiabatic electron affinity of the oligomers, the energies of vertical detachment of an electron fro m the anions (VDE), and the stability of the anions against dissociati on into individual water molecules and a free electron were estimated taking into account the second order perturbation theory (MP2) correct ions to the energy. all water anions considered are stable against dis sociation, but their VDE values are negative, and only the chain-like hexamer anion has a value of VDE close to zero, which means metastabil ity of the anion. The energy of attachment of an electron to the oligo mers is lower in the case of chain-like structures. The process is acc ompanied by structure relaxation, which is man substantial for cycles, especially for the cyclic hexamer. In the chain-like anions, the exce ss electron density is localized on the hydrogen nuclei of that termin al water molecule that acts as an acceptor of the H-bond proton, while in the cyclic anions it is distributed on the orbitals of those free hydrogen atoms that significantly approach each other due to structura l relaxation.