Theoretical studies on the reactions between 1,3-dichrolo-1, 3-diphenyl-2-azoniaallene cation and 2-methyl-1-propene

The mechanisms of reactions between 1,3-dichloro-1,3-diphenyl-2-azoniaallene cations and 2-methyl-1-propene have been explored at B3LYP/6-31G* level. It is found that the positive charge in 2-azoniaallene makes the reaction more complicated. Different reaction paths and products have been rationalized and verified. For the [2 + 2] cycloaddition reaction, [2 + 2] adduct is not stable due to larger steric hindrance, which accounts for why Hitzler's experiment did not observe the [2 + 2] product. The rate constants for the main steps are calculated with conventional transition state theory. (C) 2004 Elsevier B.V. All rights reserved.