Protonation-Induced Reversible Switching of Electronic Delocalization in a Linear Ru-Ru-Ru Complex

Area of Science:

• Inorganic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Mixed-valence (MV) complexes are crucial for understanding electron transfer phenomena.
• Molecular switches are essential components for advanced electronic devices.
• Cyanidometal-bridged complexes offer unique electronic and structural properties.

Purpose of the Study:

• To report the first molecular switch based on protonation-controlled electronic delocalization/localization in a trinuclear MV complex.
• To synthesize and characterize a novel MV complex with specific proton-accepting ligands.
• To investigate the electronic structure changes induced by protonation and electron transfer.

Main Methods:

• Synthesis and characterization of a novel LRuIII-NC-RuII-CN-RuII L (1^3+) complex.
• Protonation studies and analysis of electronic structure changes.
• Cyclic voltammetry and (TD)DFT calculations to support findings.

Main Results:

• The synthesized complex (1^3+) exhibits strong electronic delocalization between terminal Ru centers (LRuII+0.5-NC-RuII-CN-RuII+0.5L).
• Protonation of 1^3+ induces electron transfer, changing the electronic structure to HLRuII-NC-RuIII-CN-RuII LH.
• Protonation-induced electron transfer leads to a transition from delocalization to localization, with weak interaction between terminal Ru centers in the protonated form.

Conclusions:

• A reversible molecular switch based on protonation-induced electron transfer has been demonstrated.
• The study highlights the potential of cyanidometal-bridged MV complexes for molecular electronics.
• Complex 1^3+ is a promising candidate for developing advanced molecular switches.