How well can new-generation density functionals describe protonated epoxides where older functionals fail?

The performance of several density functionals are compared for the calculation of structures and energetics of protonated cyclic ethers, including epoxides. The results have shown that the newly developed DFT methods perform better that the B3LYP and the latest functional, M05-2X, has greatly improved performance for an unsymmetrical protonated epoxide.