Study on the correlation between polarizability and δ(¹H), δ(¹³C) of Al−CH₃

According to the chemical shift of ¹H NMRδ(¹H) and ¹³C NMRδ(¹³C) of Al−CH₃ of methyl-aluminum complex being easily affected by steric hindrance, induced effect (polarizability, σ_α), field-effect (σ_F) and conjugation effect (σ_R), and the main substituent effect of alkyl mainly coming from steric hindrance and polarizability, the relationship between the polarizability of alkyl and δ(¹H), δ(¹³C) of Al−CH₃ was studied from the point of view of substituents' polarizability, Hammett parameters (σ_m) and Lever parameters (E_L) of ligands. It is found that when the steric hindrance of substituents is limited, the polarizability of alkyl has a good correlation with δ (¹H) and δ (¹³C) of Al−CH₃ (pyrrolylaldiminate, R²>0.95), and the effect of substituents on δ(¹H) is greater than that of δ(¹³C). In the case of limiting the steric hindrance of substituents, the polarizability of alkyl has a good correlation with δ(¹H) and δ(¹³C) of Al−CH₃. It is suitable for multiple ligands (pyrrolylaldiminate, alcohol, β-diimine, R²>0.95). The conjugation effect of substituents and the field-effect should alleviate the effect of polarizability on δ(¹H), δ(¹³C) of Al−CH₃ (phosphorus ligand). When substituents' steric hindrance and polarizability are limited, the Hammett parameters (σ_m) of substituents and Lever parameters (E_L) of ligands are also well correlated with δ (¹H) of Al−CH₃ (phosphorus ligands, β-diketones). The study on correlation between polarizability and δ(¹H), δ(¹³C) of Al−CH₃ is suggested that δ (¹H) and δ (¹³C) of Al−CH₃ can respond to the change of substituent effect, and it has the potential to be used to study the effect of substituent effect on the ligand.