Strong Proton-Electron Coupling in π-Planar Metal Complex with Redox-Active Ligands

Area of Science:

• Coordination Chemistry
• Materials Science
• Electrochemistry

Background:

• Proton-coupled electron transfer (PCET) in metal complexes is crucial for biochemistry and catalysis.
• π-planar metal complexes with redox-active ligands are underexplored but vital for iono-electronics.
• Understanding PCET in these systems is key for advancing materials science.

Purpose of the Study:

• To investigate the proton-electron coupling of a π-planar nickel complex with redox-active N,S-ligands, Ni(itsq)₂.
• To compare the PCET properties of Ni(itsq)₂ with a similar complex bearing redox-inactive ligands.
• To explore the potential of π-planar metal complexes with redox-active ligands for novel materials.

Main Methods:

• Experimental investigation of proton-electron coupling.
• Theoretical calculations (e.g., DFT) to analyze electronic structure and orbital stabilization.
• Electrochemical measurements to determine potential shifts.

Main Results:

• Ni(itsq)₂ exhibits strong proton-electron coupling, evidenced by a significant potential shift.
• The observed potential shift is twice as large as that in [Ni(dcpdt)₂]²⁻ (a complex with redox-inactive ligands).
• Theoretical calculations confirm greater stabilization of frontier orbitals upon protonation in Ni(itsq)₂ compared to [Ni(dcpdt)₂]²⁻.

Conclusions:

• π-planar metal complexes featuring redox-active ligands demonstrate strong PCET capabilities.
• These findings highlight the potential of Ni(itsq)₂ and similar complexes for developing advanced PCET-type iono-electronic materials.
• The study opens new avenues for designing functional materials based on redox-active ligand coordination chemistry.