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An ab initio Molecular Orbital Study of tbe Cyclobutyl Anion

Wai-Kee Li ; Department of Chemistry The Chinese University of Hong Kong Shatin, N. T., Hong Kong

Sažetak

The cyclobutyl anion has been studied with ah initio molecular orbital calculation. The structures of two cyclobutyl anion conformers and some related species have been determined by full geometry optimization at the Hartree-Fock level with the diffuse-function augmented basis sets 3-21 +G and 6—31+ G*. In addition, improved energy comparisons have been obtained at the MP3/6—31+ G* level, and vibrational frequency analysis of the various species has been carried out in order to characterize the stationary points as well as to determine the zero-point vibrational energies of these species.
It has been found that the cyclobutyl anion conformer with the lone hydrogen at the anionic center occupying the equatorial position (1) is more stable than the one with hydrogen occupying the axial position (2) by 13 kJ mol-1. The transition structure for the rearrangement 2-^1 has an almost completely flattened four • -membered ring and a nearly planar geometry at the anionic center. The barrier of the rearrangement is calculated to be 24 kJ mol"1.
In addition, the calculated proton affinities for 1 and 2 are comparable to those of CH3 , C2H3', and C2H5-. Calculated electron affinities for the cyclobutyl radical indicate that, even if conformers 1 and 2 are stable towards spontaneous electron loss, their ionizations potentials should be very low.

Ključne riječi

Hrčak ID:

137395

URI

https://hrcak.srce.hr/137395

Datum izdavanja:

10.8.1990.

Posjeta: 507 *