Why Is the Concerted (2+2) Mechanism of the Reactions of SO3 with Alkenes Favored over the (3+2) Mechanism? Density Functional and Correlated ab Initio Calculations and a Frontier MO Analysis

Abstract

The (2+2) cycloadditions of SO3 to ethene, propene, and 2-methylpropene were investigated with Hartree−Fock, MP2, QCISD(T), and hybrid Hartree−Fock/density functional theory (HF-DFT) methods. Exper...