Influence of internal electrostatics on reduction potentials in amine-ligated bimetallic copper complexes

Area of Science:

• Electrochemistry
• Computational Chemistry
• Catalysis

Background:

• Modulating redox potentials of molecular electrocatalysts is key to minimizing overpotentials.
• Electrostatic interactions, particularly from s-block cations, are known to tune single-site catalyst redox potentials.
• The role of electrostatic effects in bimetallic complexes remains less explored.

Purpose of the Study:

• To quantify the influence of distance-dependent electrostatic effects on the reduction potentials of bimetallic copper complexes.
• To investigate how varying linker lengths impact these electrostatic interactions.
• To experimentally validate computational predictions.

Main Methods:

• Density functional theory (DFT) calculations.
• Electrostatic charged sphere models.
• Synthesis and cyclic voltammetry of bimetallic copper complexes.

Main Results:

• Reduction potentials varied linearly with the reciprocal of the Cu-Cu distance (slope: 4.1 V Å).
• A span of over 500 mV in reduction potentials was observed, indicating strong coulombic interactions.
• Computational predictions were experimentally validated for different linker lengths.

Conclusions:

• Distance-dependent electrostatic interactions significantly tune redox potentials in bimetallic systems.
• The findings provide a framework for designing electrocatalysts by controlling metal-metal distances.
• This work highlights the importance of electrostatic modulation in bimetallic electrocatalyst design.