Substituent Effects on the Vinylcyclopropane–Cyclopentene Rearrangement – A Theoretical Study by Restricted and Unrestricted Density Functional Theory

✍ Scribed by Dirk Sperling; Jürgen Fabian

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 172 KB
• Volume: 1999
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/(sici)1099-0690(199901)1999:1<215::aid-ejoc215>3.0.co;2-m

✦ Synopsis

The effect of donor substitution by the hydroxy group and of closely connected with the radical stabilizing properties of the substituents. As indicated by singlet/triplet splitting acceptor substitution by the cyano group on the activation energies of the vinylcyclopropane-cyclopentene rearrange-energies, the transition structures are essentially biradicaloid. In spite of spin pairing in the transition structure ment was calculated by the spin-restricted RB3LYP/6-31G* method for reactant structures and by the spin-unrestricted the substituent effects on bond lengths and on stabilization energies are very similar to those of the free radicals UB3LYP/6-31G* method for transition structures. The activation energies of the rearrangement of hydroxy-and corresponding to the two radical substructures. Thus, the transition structures may be considered, in good cyano-substituted vinylcyclopropanes are very similar for substitution in the same position. In agreement with earlier approximation, as structures consisting of two weakly interacting radicals. findings the substituent effects on the activation energies are