We now turn our focus to comparisons between the minimal models in Figure to determine which molecular features alter the reactivity and to what extent. Specifically, these model systems permit the separate investigation of the choice of linker atom (N vs P), their coordination (c 3 vs c 4 ), and the bite angle. Therefore, in addition to the P(c 4 ) models discussed in the previous sections, ∆∆E R Y values were also computed for models with Y = P(c 3 ), N(c 4 ), and N(c 3 ). We plot ∆∆E R Y for each reaction and each type of model complex in Figure .