HDF and QCI studies on the heterosubstituted iminoxy radicals: substituent effect on the isotropic hyperfine couplings with 13C and 1H nuclei

Isotropic hyperfine parameters of a set of iminoxy radicals are investigated using hybrid density functional and quadratic configuration interaction methods. The systems studied are R1R2CNO radicals, where R1H, BH2, CH3, NH2, OH, F, AlH2, SiH3, PH2, SH, Cl and R2H. Theoretical results indicate that magnitude of the hyperfine coupling with iminoxy 13C nucleus due to the particular isomer of the radical is strongly affected by electronegativity of the substituents R1 and R2. Aiso(13C) varies from 6.7 to 56.2 G for Z (and from 45.6 to 18.7 G for E) isomers of the iminoxyls depending on the substituent (AlH2 and F, respectively).