Theoretical Calculations of Kinetic Isotope Effects for a Series of Aziridines

The nitrogen inversion in aziridine and som parent substituted aziridines is investigated using various computational methods. The stationary points on each potential energy surface are optimized using the B3LYP functional of density functional theory (DFT) in conjuction with the popular 6-31G(d) basis set. Rate constants and thereby kinetic isotope effects (KIEs) are computed at different temperatures using transiton state theory (TST) and various techniques of variational transition state theory (VTST). Moreover, corrections are made for tunneling and non-classical reflection, using three semiclassic correction methods: the Wigner tunneling correction as well as the zero-curvature and the samll-curvature corrections. The performance of the various methods to compute KIEs are compared and the effects of tunneling are discussed.