Electronic structure calculations of 1,3‐dipolar cycloadditions using density functional and Hartree–Fock methods

Abstract

AbstractLocal spin density (LSD) methods were used to study the concerted 1,3‐dipolar cycloadditions for fulminic acid plus acetylene, fulminic acid plus ethylene, and nitrone plus ethylene. Cartesian Gaussian double‐zeta split‐valence basis sets augmented with one set of polarization functions (DZVP) were used for the LSD calculations. The LSD calculations were performed with the LSD exchange functional (Dirac) and with the Vosko, Wilk, and Nusair correlation energy functional (VWN). Nonlocal spin‐density corrections (NLSD) were estimated with the exchange functional of Becke and the correlation energy functional of Perdew (VWN + BP) and Becke, and the correlation energy functional of Lee, Yang, and Parr (B‐LYP). Vibrational frequencies were computed at the VWN and B‐LYP levels by numerical differentiation of the analytical first derivatives of the energy. Each of these reactions was examined using Hartree–Fock and Møller–Plesset perturbation theory for comparison. Geometry optimizations were carried out at the Hartree–Fock level with the 6‐311G(d,p) basis set, and correlation energies were computed up to the MP4SDTQ/6‐311G(d,p) level of theory. For the reactions of fulminic acid plus acetylene, fulminic acid plus ethylene, and nitrone plus ethylene, our best estimated density functional barrier heights are 7.8 ± 1.5, 8.9 ± 0.3, and 11.05 ± 1.9 kcal/mol, respectively. These results are in reasonable agreement with the correlated wave‐function calculations and experimental estimates. © 1994 John Wiley & Sons, Inc.