Catalytic Carbon−Halogen Bond Activation: Trends in Reactivity, Selectivity, and Solvation

摘要: We have theoretically studied the oxidative addition of all halomethanes CH3X (with X = F, Cl, Br, I, At) to Pd and PdCl-, using both nonrelativistic zeroth-order-regular-approximation-relativistic density functional theory at BLYP/QZ4P. Our study covers gas phase as well condensed (water), where solvent effects are described with conductor-like screening model. The activation C*−X bond may proceed via two stereochemically different pathways:  (i) direct insertion (OxIn) which goes retention configuration C* (ii) an alternative SN2 pathway inversion C*. In phase, for Pd, OxIn has lowest reaction barrier CH3X's. Anion assistance, that is, going from changes preference CH3X's pathway. Gas-phase barriers pathways C−X generally decrease descends in group 17. Two striking th...