DFT Study on Homolytic Dissociation Enthalpies of C-I Bonds

The C-I bond dissociation enthalpies (BDE) of various organic iodides were calculated using high-level theoretical methods including MP2 and CCSD(T) with extrapolated basis set as well as a number of density functional theory methods. After systematic evaluation of the theoretical results against available experimental C-I BDEs, it was found that the MPW-LYP1M method gave the lowest root mean square error. We, therefore, used this method to examine the substituent effects on different categories of C(sp³)-I and C(sp²)-I bonds. Fur-thermore, the remote substituent effects on the C-I BDEs of substituted iodobenzenes and substituted (iodomethyl)benzenes were also investigated at the same level. The C-I BDEs of typical heteroaromatic iodides including five-membered and six-membered heterocyclic iodides were also examined.