Hammett and Brown correlations in the structure and electronic properties of H₂Si=SiHAr (Ar = p‐C₆H₄X; X = NH₂, OH, Me, H, F, Cl, CHO, COOH, CN, NO₂) molecules

Abstract

Substituent effect on the structure and electronic properties of H2Si=SiHAr (Ar = p‐C6H4X; X = NH2, OH, Me, H, F, Cl, CHO, COOH, CN, NO2) molecules are studied at the CAM‐B3LYP/6‐311G(d,p) level of theory. Energy decomposition analysis (EDA) is used as a useful tool for illustrating the interaction between H2Si and SiHAr fragments in HArSi=SiH2 molecules. Energetic analysis reveals that the singlet state of the fragments is more stable than triplet state. Also, interactions are stronger in the presence of electron‐withdrawing groups (EWGs) in comparison to electron donating groups (EDGs). EDG and EDG effects are investigated on the stability of fragments, frontier orbital energy, distortion, HOMO–LUMO gap, electron‐donating (ω−) and electron‐accepting (ω+) powers of the studied molecules. Then, the correlations between these calculated parameters with the Hammett and Brown constants (σp and σp+, respectively) are provided. Also, time‐dependent density functional theory method (TD‐DFT) is employed for the determination of the strongest absorption band values (λmax,el) of these molecules. This absorption band is attributed to the HOMO →LUMO transition.