Quantum-chemical study of halophilic interactions: III. Ab initio study ofthe attack of tetrachloromethane by halide ions

Ab initio calculations of the model reactions of tetrachloromethane with ch loride and iodide anions showed that attack of the carbon atom in accordanc e with the S(N)2 mechanism in the initial stage gives rise to weakly bound complexes of CCl4 with halide ions. Further transformation of these complex es is limited by large potential barriers. Attack of the nucleophile at the chlorine atom to give stable complexes CCl3-Cl-Hlg(-) is preferable, in co ntrast to reactions of halide ions with CH3Cl in which the nucleophilic att ack is directed solely at the carbon center. For the iodine atom hound to t he carbon center the halophilic attack becomes feasible even with CH3I.