title: The C4H7+ cation.  A theoretical investigation.
abstract: The potential energy surface of the C4H7+ cation has been investigated with ab initio quantum chemical theory.  Extended basis set calculations, including electronic correlation, show that cyclobutyl and cyclopropylcarbinyl cation are equally stable isomers.  The saddle point connecting these isomers lies 0.6 kcal/mol above the minima.  The global C4H7+ minimum corresponds to the 1-methylallyl cation, which is 9.0 kcal/mol more stable than the cyclobutyl and the cyclopropylcarbinyl cation and 9.5 kcal/mol below the 2-methylallyl cation.  These results are in excellent agreement with experimental data.
authors.affiliation: IBM Almaden Research Center, San Jose, California 95120-6099, USA.
authors.forename: W
authors.initials: W
authors.lastname: Koch
authors.forename: B
authors.initials: B
authors.lastname: Liu
authors.forename: D J
authors.initials: DJ
authors.lastname: DeFrees
mesh_terms: D002244:Carbon; D002412:Cations / Q000032:analysis* / Q000737:chemistry*; D003500:Cyclization; D006859:Hydrogen; D007536:Isomerism; D008956:Models, Chemical
chemical_list: D002412:Cations; D002244:Carbon; D006859:Hydrogen