Theoretical correlations of stretching force constants and lengths of bonds in ion–molecule clusters and transition states of methyl-transfer reactions

Abstract

The 4-31 G level of computation has been found to be adequate in reproducing the empirical a_ij and b_ij parameters of ‘Badger's rule’ for 1–1 series of diatomics. The greater theoretically determined parameters a_ij indicated that the valence shall of the central carbon in the transition state of the identity reaction X^–+ CH₃X ⇌ XCH₃+ X^– has been expanded dramatically, and the larger values of b_ij correctly reflect the greater bond compressibility of the longer bonds in the ion–molecule clusters. A satisfactory correlation has been obtained between the intrinsic barrier ΔE^*_xx and the square of the bond length d_x.