Why metal–oxos react with dihydroanthracene and cyclohexadiene at comparable rates, despite having different C–H bond strengths. A computational study

Abstract

1,4-Cyclohexadiene (CHD) and 9,10-dihydroanthracene (DHA) are two substrates used to probe the steric requirements of metal–oxo oxidants in H-atom-transfer (HAT) reactions, based on the assumption that they have comparable C–H bond dissociation enthalpies (BDEs). We use computations to demonstrate that the BDE of DHA is ∼3.5 kcal mol⁻¹ larger than that of CHD and that their often comparable reactivity is based on a competing interplay of bond strengths and favorable van der Waals interactions.