MOLECULAR-STRUCTURES AND CONJUGATIVE INTERACTIONS IN VINYLCYCLOPROPANE AND CYCLOPROPYL CYANIDE

Ab initio calculations of approximately double zeta quality, including complete geometry optimization by the gradient procedure, have been carried out on vinylcyclopropane and cyclopropyl cyanide. As in similar previous studies on substituted cyclopropanes, a high degree of reliability has been achieved in the computed differences in ring CC bond lengths, leading to accurate determination of ring asymmetry induced by interaction with the substituent. For the present compounds, the first compounds with unsaturated substituents to be investigated by this method, the computed orbital populations, gross atomic charges, and induced ring asymmetry all point to a conjugative interaction between the pi orbital of the substituent and a sigma (Walsh-type) orbital of the ring. © 1979.