We have studied the transmission of electrical effects [1-4] as a function of substituent chemical shifts, scs, in ¹H, ¹³C, and ¹⁹F NMR spectra of XGY in which X is the substituent, Y is the atom responsible for the chemical shift and G is the skeletal group to which X and Y are bonded. The C atom of G which is bonded to X is sp² hybridized. We have shown that L values obtained from correlation with the LDR equation are a measure of the magnitude of electrical effect transmission. Preliminary results for correlation of -L values of XG-¹⁹F scs with the equation

log (-L) = a₁ log n + a⁰ (1)

gives the regression equation (2) on exclusion of the value for G of 6,2-naphthalene.

log (-L) = -3.20 (± 0.580) log n + 2.99 (± 0.401) (2)

r², 83.59; F, 30.56; S_est. 0.206; S⁰, 0.468; N_dp, 8 .

This corresponds to a modified field effect with a dependence on 1/r³.

We have also examined the composition of the group electronegativity parameters often used in the description of ¹⁹F scs. They are a function of electrical effect and polarizability parameters [5]. The regression equation is:

σ_χ = 0.424(± 0.107) σ_e - 0.329 (± 0.0929)σ_d -1.10(± 0.468) (3)

R², 84.23; A100R², 81.36; F, 17.80; S_est, 0.0897; S⁰, 0.470; N_dp, 14.

It seems likely that there is at least one additional variable as yet undiscovered.

[1] M. Charton, J. Phys. Org. Chem. 1999, 12, 275-282: The Nature of Electrical Effect Transmission.

[2] M. Charton, B. I. Charton, J. Chem. Soc. Perkin Trans. 2, 1999, 2203-2211: The Mode of Transmission of Electrical Effects.

[3] M. Charton, Coll. Czechoslov. Chem. Commun. 1999, 64, 1849-1876: The Nature and Transmission of Substituent Electrical Effects in Alicyclic Solvolysis.

[4] M. Charton, B. I. Charton, J. Phys. Org. Chem. 2001, 14, 832-838: The Mode of Transmission of Electrical Effects. Evidence from Infrared Stretching. Frequencies.

[5] W. Adcock, J. E. Peralta, H. Ruben. Magn. Res. Chem. 2003, 41, 503-508: Computation and Analysis of ¹⁹F Substituent Chemical Shifts of Some Bridgehead-Substituted Polycyclic Alkyl Fluorides.

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