DFT Study on Homolytic Dissociation Enthalpies of C—I Bonds

Abstract

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. Furthermore, 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.