Theoretical studies on the kinetics of ring opening of 1-bicyclo[2.1.0]-pentanylmethyl, 1-bicyclo[3.1.0]-hexanylmethyl, and 1-bicyclo[4.1.0]-heptanylmethyl radicals

By carrying out B3LYP calculations, we have performed a detailed mechanism study on the 1-bicyclo[n.1.0] (1-bicyclo[2.1.0]-pentanylmethyl, 1-bicyclo[3.1.0]-hexanylmethyl, and 1-bicyclo[4.1.0]-heptanylmethyl) radicals ring opening reaction in THF solvent. We calculated the rate constants for the reactions. Our calculations are consistent with the experimental results that the expansion pathway is favored both kinetically and thermodynamically compared with the non-expansion pathway for the 1-bicyclo[n.1.0] radical ring opening reaction. Our calculated results also show that with the ring size decreasing, the ring-expansion for the 1-bicyclo[n.1.0]-hexanylmethyl radical ring opening reaction becomes easier kinetically and thermodynamically. We would expect that the accurate calculation results for the model systems will be useful for the experimental researchers working in this field.