Fig. 4. Isotropic chemical shift (δ) versus calculated isotropic shielding (σcalc). For model complexes the chemical shift values were predicted using a calibration method based on B3LYP as functional. Experimentally obtained values15 are labelled with ‘exp’ (OAr = 2,6-di-tert-butyl-4-methylphenoxy). (a) Electronegativity and steric effects, (b) gradual substitution of alkyl ligands by amido ligands, and (c) effect of coordination geometry.
