Heterogeneous electron-transfer rate constants for M2(O2CR)4(0)/+, where M = Mo, W, Ru, or Rh and R = alkyl or aryl.

Area of Science:

• Inorganic Chemistry
• Electrochemistry
• Coordination Chemistry

Background:

• Dinuclear metal complexes with M2(O2CR)4 cores are important in various chemical applications.
• Understanding their electron-transfer properties is crucial for designing new materials and catalysts.
• Previous studies have explored electron transfer in related systems, but a systematic investigation of M2(O2CR)4 complexes is needed.

Purpose of the Study:

• To determine the heterogeneous electron-transfer rate constants (ks) for the oxidation of M2(O2CR)4 complexes.
• To investigate the influence of the metal center (M = Mo, W, Ru, Rh) and the carboxylate ligand (R = alkyl, aryl) on electron-transfer kinetics.
• To compare the obtained rate constants with those of other well-known redox systems.

Main Methods:

• Nicholson's method was employed to determine heterogeneous electron-transfer rate constants (ks).
• Electrochemical experiments were conducted in benzonitrile solvent.
• The influence of added ligands on redox potentials (E1/2) and electron-transfer rates was studied.

Main Results:

• The electron-transfer rate constants (ks) for M2(O2CR)4 complexes were successfully determined.
• For R = tBu, the ks values followed the order M = Mo > W > Ru > Rh.
• Added ligands influenced E1/2 values based on their basicity and suppressed electron transfer rates.

Conclusions:

• The metal identity plays a significant role in dictating electron-transfer rates in these dinuclear complexes.
• The nature of the carboxylate ligand (R) does not show a simple correlation with electron-transfer kinetics.
• Ligand binding can modulate redox properties and hinder electron transfer, offering insights into redox control mechanisms.