PO bond dissociation enthalpies: High-level ab initio and DFT study

The PO bond dissociation enthalpies (BDE) were calculated using high-level ab initio methods including G3, G3B3, CBS-Q, CBS-4M, CCSD(T), and MP2. Based on the comparison of these theoretical values and experimental ones, the performances of a number of density functional theory (DFT) methods were then assessed. It was found that the B3P86 method gave the lowest root of mean square error. We, therefore, used this method to calculate the PO BDEs of a number of substituted organophosphorus compounds. The electronic effect of the substituents and the remote substituents effect of aryl substituted organophosphorus compounds on PO BDE were investigated. After natural bond orbital analysis, a quantitative relationship between PO BDEs and the corresponding atomic charges was determined. In addition, a molecular orbital analysis of typical molecules was conducted in order to investigate the electronic effect on PO BDEs.