Structure and molecular rearrangements of ethylidene and propylidene in the unrestricted Hartree—Fock approach

Abstract

The structures of singlet ethylidene and propylidene, as well as their intramolecular rearrangements to ethylene and to propylene and cyclopropane, respectively, have been calculated using the spin-unrestricted Hartree—Fock (UHF) method within the MINDO/3 approximation. Both alkylcarbenes are predicted to be stationary points on the corresponding potential-energy surfaces, and to have a significant biradical character. Their conversion into alkenes presents a small non-zero energy barrier, in agreement with the results of recent deuterium isotope effects.