2-STEP SEQUENCES WITH EXTENDED TEMKIN NONUNIFORM REACTIVITY - RATE-DETERMINING STEP REVISITED

Within the Temkin-type approach for two-step mechanisms, the problem o f the rate-determining step (rds) and its possible shift on a nonunifo rm surface is reexamined. The nonuniformity concept is extended to its maximum limits and a new transfer rule is derived for the model's int rinsic linear free energy relationships. For any thermodynamically all owable coupling of the two steps, this provides a quantitative estimat ion of rds shift, which is unimportant for reasonable model parameters . The proposed transfer rule leads to a unique analytical solution for the local turnover rate, whatever the steps' coupling. Copyright (C) 1996 Elsevier Science Ltd