STRUCTURAL PECULIARITIES AND THE POSSIBILITY OF THE EXISTENCE OF SMALL WATER CLUSTER ANIONS (H2O)(N)(-) WITH N-LESS-THAN-OR-EQUAL-TO-4

Structures of (H2O)(n)(-) anions with n less than or equal to 4 were o ptimized at the UHF/4-31++G* level and their stability was estimated at the MP2/4-31++G* level, The trimer anion has a chainlike structure , while the tetramer anion can exist either in a chain-like or a cycli c configuration. In the dimer anion and in the chain-like anions, the excess electron density is localized an the terminal water molecule, a n acceptor of the H-bond proton. In the cyclic anion, it is uniformly distributed over the free hydrogen atoms. All considered anions have e nergy values higher than those of the corresponding neutral oligomers. The detachment of an electron from the anions should proceed with the liberation of energy. However, trimer and larger anions are stable ag ainst dissociation into individual water molecules and a free electron .