A Theoretical Investigation of Substituent Effects on the Electronic Spectra of Antimony( III ) Corrolates

ABSTRACT Sb(III) corrolates show single/double Soret bands depending on peripheral substituents. To clarify the mechanism, all‐electron realistic TDDFT calculations and wave function analyses are performed on a series of Sb(III) corrolates bearing different meso ‐substituents. The results indicate that the split mainly stems from the large transition energy gap (Δ E ) between S 0 → S 3 (HOMO → LUMO + 1) and S 0 → S 4 (HOMO‐1 → LUMO + 1) excitations, enlarged with the macrocyclic electron density increasing. The large oscillator strength difference (Δ f ) plays a secondary role in the detectable split at a close Δ E . Sb atom contributes significantly to the inner orbitals (HOMO‐2/HOMO‐7/HOMO‐8). Decomposition of the total transition dipole moment ( μ T ) demonstrates that transitions related to these orbitals induce non‐negligible negative contributions to the μ T of S 0 → S 4 excitation, thereby reducing the oscillator strength. The less electropositive Sb atoms trigger the more obvious offsetting effects. In conclusion, electron‐donating groups (EDGs) lower the Δ E and Δ f of Sb(III) corrolates, leading to splitting Soret bands.