Investigation of electronic structure and proton transfer in ground state acetylacetone

Various quantum chemical methods, including Hartree–Fock (HF), density functional (DFT/B3LYP), Møller–Plesset perturbation (MP2), and coupled-cluster [CCSD, CCSD(T), CC3] schemes, have been exploited with correlation-consistent basis sets in an attempt to resolve controversies surrounding the equilibrium structure of ground-state acetylacetone. Geometry optimizations performed at the CCSD(T)/aug-cc-pVDZ level of theory predict a global minimum-energy configuration of Cs symmetry that exhibits an interoxygen distance of 2.575 Å, with the symmetric (C2v) transition state for proton transfer presenting a potential barrier of 1276.7 cm−1 height. The resulting theoretical description of acetylacetone is in excellent agreement with recent electron diffraction experiments.