1H-Cyclopropa[b]naphthalene (3H) and 2-methylnaphthalene (6H) were deprotonated by fluoride ion in a Fourier transform mass spectrometer, and their acidities were measured via equilibrium techniques (ΔG°acid=357.5±2.1kcal mol-1 (3H) and 365.2±2.1kcal mol-1 (6H), ΔH°acid=365.1±2.1kcal mol-1 (3H) and 372.7±2.1kcal mol-1 (6H)). These results were modeled by MP2 and BVWN5 calculations, and additional computations were carried out on benzocyclopropene (1H), toluene (2H), 1H-cyclopropa[a]naphthalene (4H), and 1-methylnaphthalene (5H). The stability of the conjugate bases of 3H and 4H are examined and their aromatic vs. antiaromatic nature is considered.
Bibliographical noteFunding Information:
Support from the National Science Foundation, the donors of the Petroleum Research Foundation, as administered by the American Chemical Society, the Minnesota Supercomputer Institute, and the University of Minnesota-IBM Shared Research Project are gratefully acknowledged. The work in Zagreb (I.A., Z.G., and M.E.M.) has been supported by the Ministry of Science and Technology of Croatia through project 00980801 and HR-US project JF 143.
- Ab initio
- DFT calculations