σ-Participation — A Factor in Fast Rates?

Abstract

The results discussed in Chapter 2 clearly establish the importance of relief of steric strain in the fast rates of solvolysis exhibited by a number of sterically crowded systems. However, as was pointed out in Chapter 1, the development of the concept of σ-bridging in the early 1950s and its growing utilization to reinterpret the structures of carbonium ions led to increasing numbers of proposals attributing enhanced rates in such systems not to relief of steric strain but to the stabilization provided by the σ-bridge.