Concerted addition potential energy surfaces

A comparative ab initio study [22] on these two alternative reaction pathways concludes that a zwitterionic structure of the type suggested by Westheimer is not a stationary point on the explored potential energy surfaces for the systems H2O + (H0)2P(0)H and H2O + (H0)3P(0). Two types of critical points were found for these model systems. The first type corresponds to transition structures for the concerted addition of water to these phosphoryl compounds (Figure 3.1). 

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