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tributed to larger resonance energy in benzene as opposed to benzene iron tricarbonyl. ConclusionsThe ab initio calculations seem to represent the ground state and transition state of bicyclo[2.2.1]hepta-2,5-dien-7-one reasonably well. The ground-state geometry with symmetry seems reasonable when compared to similar molecules whose geometry is known, and leads to calculated IR spectra of bicyclo[2.2.1]hepta-2,5-dien-7-one and bicyclo [ 2.2.1 ] hepta-2,5 -dien-7 -onewhich closely match the experimental ones. This geometry appears distorted toward products, which in turn suggests that the transition state is symmetrical. A transition state with C^symmetry is indeed found. This appears to be a transition state when correlation effects are included at the MP2/4-31G level as well. Furthermore, the activation energy at the MP3/6-31G* level agrees quite closely with the experimental value, and reasonable extrapolation to the MP4/6-31G* level suggests that one should expect even better agreement there. While a nonsynchronous transition state is found at the UHF/STO-3G level, this does not persist at higher levels. The

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The properties of a molecule are determined by the distribution of its electrons. This distribution can be described by the charge density, which is readily obtained from the wave functions derived by ab initio molecular orbital calculations. The charge density may be analyzed in a number of different fashions to give information about the effects of substituents, structural changes, and electronic excitation on the properties of molecules; one common procedure makes use of projection density or charge difference plots. Charge density also may be partitioned among atoms, and by numerical integration over appropriate volume elements one may obtain atomic charges, dipoles, kinetic energies, and other properties of the atoms in a molecule. Many chemical phenomena have been analyzed in terms of charge densities.

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