Gas phase reactions of nitromethyl carbanion with CHCl3 and CCl4: A theoretical investigation

Abstract The ion/molecule reactions of CH 2 NO 2 - with CCl 4 and CHCl 3 in gas phase have been theoretically investigated using BH&HLYP, B3LYP and MP2 methods with 6-31+G ∗ and 6-311+G ∗∗ basis sets. The experimentally observed H/Cl exchange reaction between CH 2 NO 2 - and CCl 4 was found to include two individual reactions, the chlorine cation transferring from CCl 4 to CH 2 NO 2 - via a chlorine-attack transition state and the proton transferring from CH 2 ClNO 2 to CCl 3 - via a proton-attack transition state. The calculated energies indicate that the H/Cl exchange is both kinetically and thermodynamically favorable. The H/Cl exchange reaction was found to be also possible for CHCl 3 , but a notable activation barrier represented by a bridge-like transition state and strong endothermicity for the chlorine cation-transfer step make this reaction impossible under low-energy condition. The classic S N 2 reactions between CH 2 NO 2 - and the two chloromethanes were also calculated and notable energy barriers were identified for them.