AB-INITIO STUDY OF NITROMETHANE DEPROTONATION BY (OH)(-)CENTER-DOT-NH(2)O CLUSTERS

The deprotonation of nitromethane by (OH)(-). nH(2)O clusters has been studied. Ab initio quantum chemistry calculations including electron correlation are used to determine the geometries, energetics, and natu ral bond orbital electronic populations of reactants, transition state s, and products for the cases of n = 0 and n = 2. An analysis of the n egative charge redistribution during the reactions is given. In partic ular, special attention is devoted to the evolution of the negative ch arge on carbon, which has been implicated in the past in the observed anomalous values of the Bronsted parameter in the reaction of interest , the so-called ''nitroalkane anomaly''. Finally, the deprotonation of nitromethane by (OH)(-) is compared with the analogous reaction invol ving acetonitrile; the results suggest that the high electron affinity of the NO2 group is critical for the existence of the nitroalkane ano maly.