Why Metal-Oxos React with Dihydroanthracene and Cyclohexadiene at Comparable Rates, Despite Having Different C–H Bond Strengths. A Computational Study

Klein, J. E. M. N.; Dereli, B.; Que, L., Jr. ; Cramer, C. J.
Chem. Commun. 2016, 52, 10509 (doi:10.1039/c6cc05395e).

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 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.