LOCAL ORBITAL GUIDE TO ALLOWED INTERCONVERSIONS OF C4H7+ IONS

A guide to adiabatic reaction pathways, parallel to the method of Hoffmann and Woodward but convenient for three-dimensional molecules of low symmetry, is developed in terms of localized molecular orbi tals. Calculations on the C4H7+ system illustrate the technique; several predictions are made. The syn-allyl carbinyl ion closes to cyclobutyl ion by a disrotatory motion. The cyclopropylcarbinyl cation rearranges to a nonplanar cyclobutyl ion by bending the exo-methylene toward a ring carbon. The CH bond at the formally charged carbon naturally assumes the axial position essential to a stable cyclobutyl ion. The protonated planar methylene cyclopropane may undergo a pseudorotation by conrotatory motion of the exo- and a ring methylene. A detailed description of derealization in these ions is given by a newly developed semiempirical local orbital analysis. © 1969, American Chemical Society. All rights reserved.