On the fragmentation pathway of the ionized enol of glycine in the gas phase

Density functional and second-order many body perturbation approaches were used to compute the potential energy surface for the fragmentation of the i onized enol of glycine [H2NCH = C(OH)(2)](+.) into water and aminoketene ra dical cation [H2N-HC = CO](+.). Two possible pathways were considered. The potential energy surfaces obtained are very similar and both predict the ex istence of a molecular complex in which the water is coordinated to the ami noketene moiety in two different fashions with a noticeable binding energy. The fragmentation is kinetically controlled by the step in which the molec ular complex is formed from the most stable cation enol of glycine. Our qua ntum-mechanical data confirm the hypothesis that the ylide ion [H3NCHCOOH]( +.) is an intermediate in the water loss. Copyright (C) 2001 John Wiley & S ons, Ltd.