Accurate Prediction of Au[BOND]P Bond Strengths by Density Functional Theory Methods



The recent development of Au-catalyzed reactions has greatly enriched the methods of organic synthesis. The phosphine or phosphate-coordinated Au complexes have shown high efficiency in catalyzing various C[BOND]C and C[BOND]H activations. In many of these reactions, the Au[BOND]P bond strength was found to play an important role in determining the catalytic efficiency. In the present study, the accuracy of different theoretical methods for prediction of Au[BOND]P strengths has been examined on basis of the experimental enthalpy changes between different ClAu(PR3) and ClAu(THT) (THT=tetrahydrothiophene). By comparing the different DFT functionals (e.g. B3LYP, TPSS, M06), different basis sets (including the different effective core potentials on Au and the total electron basis sets on all other atoms), and different solution phase single point calculations, we found that the TPSS/(CPE-121G+f:6-311+G(d,p)(SMD)//TPSS/(CPE-121G:6-31G(d) (M1) method gives the best correlations with the available experimental results. Meanwhile, the calculations with B3LYP//TPSS and M05//TPSS also give comparable calculation results. Finally, the specified method (M1) is used to calculate the Au[BOND]P bond dissociation enthalpies and energies of different ClAu(PR3)/ClAu(P(OR)3) complexes. By accurately reproducing the available experimental results, we believe that the method (M1) is reliable for the theoretical analysis of Au-P systems.