Density functional theory investigation of the reactions of CH2Br-I, CH2I-Br, CH2Cl-I, and CH2I-Cl isopolyhalomethanes with ethylene

Abstract

We report density functional theory calculations that examine the chemical reactivity of the iso-CH 2X-I and iso-CH 2I-X (where X = Br or Cl) species with ethylene and their isomerization reactions. The carbenoid properties and isomerization reactions of these CH 2X-Y species were compared to those found previously for the CH 2X-X species (where X = I, Br or Cl). The chemical reactivity of the iso-CH 2X-I and iso-CH 2I-X species varies with the electronegativity of the X atom and the position of the X atom in the carbon-halogen-halogen moiety. In addition, the C-X-I or C-I-X bond angles and I-X bond lengths (which vary more than in the iso-CH 2X-X species) also appear to influence the chemical reactivity of the iso-CH 2X-I and iso-CH 2I-X species. We briefly discuss the properties of these cyclopropanation and isomerization reactions and likely consequences for using different isopolyhalomethanes and other species as methylene transfer agents.