EFFECT OF SOLVATION ON THE SHAPES, SIZES, AND ANISOTROPIES OF POLYATOMIC ANIONS VIA MOLECULAR ELECTROSTATIC POTENTIAL TOPOGRAPHY - AN AB-INITIO SELF-CONSISTENT REACTION FIELD APPROACH

The effect of solvation, as studied by the self-consistent reaction fi eld procedure, on the shapes, sizes, and anisotropies of eight small p rototypical anions (OH-, NH2-, CH3-, CN-, SH-, N-3(-), NO2-, and NO3-) has been studied at the ab initio 6-31++G(d) level. Both the general molecular electrostatic potential distribution and the molecular elect rostatic potential topography have been used for examining the effect of solvation. The results demonstrate both the complexity and specific ity of the hydration effect on the solute charge distribution. It is o bserved that in general anions tend to shrink upon solvation. The mole cular electrostatic potential, in general, becomes more negative and t he electron density is increased upon solvation. The effect of the sol vation on the chemical reactivity and anisotropy of the anions in aque ous environment is discussed.