Abstract: An equation: δ_cal=δ_0n+Δα+Δβ+Δγ+c, for the calculation of ¹⁵N chemical shifts of substituted imines was provided. The five substituent parameters were obtained by linear least square regression analysis on the data from four different kinds of imines (PhCH=N-X, RHC=NC₆H₅, RHC=NCH₃ and RHC=N-i-C₃H₇). The accuracy of the results calculated with the model was checked using 34 ¹⁵N NMR chemical shifts in 34 substituted imines as a test set. The confidence limit was found to be 99.5%, and the calculating errors for about 95% of the compounds were less than 3.0 (with relative errors of 0.3%). The effects of p-substituent on the chemical shifts of the ¹⁵N atoms of aromatic imines were also analyzed.

Key words: ¹⁵N NMR, chemical shift, substituent effect, imines