Toward an expanded oxygen atom transfer reactivity scale: Computational investigation of the energetics of oxo transfer reaction couples

The computational prediction of gas phase enthalpy (neutral substrates) and aqueous free energy (anion substrates) changes has been evaluated for the oxygen atom transfer reaction X + 1/2O₂ → XO. Several density functionals (SVWN, BP86, B3LYP) at double- and triple-ζ levels were surveyed, along with one composite ab initio method (G3(MP2)). Results are presented for extensive main group test sets for which experimental thermochemistry is available. In addition, several minimal reaction couples of the type [M^IVOL₂]/[M^VIO₂L₂] (M = Mo, W) have been examined. Overall, the results suggest a computational approach to the energetics of oxo transfer is feasible, potentially affording an expanded oxo transfer reactivity scale.