S=O homolytic bond dissociation enthalpies in sulfones: high-level ab initio and DFT study

The S=O bond dissociation enthalpies (BDE) of sulfone derivatives were calculated using high-level ab initio methods including G3, G3B3, CBS-Q, CBS-4M and MP2. Based on the comparison of these theoretical values and experimental ones, the performances of a number of density functional theory methods were then assessed. It was found that the KMLYP method gave the lowest root mean square error. We, therefore, used this method to calculate the S=O BDEs of a number of substituted sulfones. The electronic effect of the substituents and the remote substituent effect of aryl-substituted sulfones on S=O BDEs were investigated. In addition, a molecular orbital analysis of typical molecules was conducted in order to investigate the electronic effect on S=O BDEs. We also predicted several S=O BDE values of heteroaromatic-substituted sulfones using the KMLYP method. [GRAPHICS] .