Theoretical investigation of the first hyperpolarizability redox-switching in a ruthenium complex

- The first hyperpolarizability of a redox switching RuII/III complex has been investigated.
- Both TDDFT and SOS methods confirm and explain experimental β contrast.
- MLCT state dominates RuII β whereas ILCT contribution is negligible.
- MLCT state disappears and β drops substantially upon oxidation.
- The depolarization ratio changes little upon oxidation.