High yield syntheses of stable, singly bonded Pd2(6+) compounds

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Coordination Chemistry

Background:

• Palladium chemistry is crucial for catalysis and materials science.
• The synthesis of low-valent palladium clusters, especially those with metal-metal bonds, presents unique challenges.
• Understanding the electronic structure and stability of palladium compounds is key to their application.

Purpose of the Study:

• To establish a general synthetic route for dipalladium compounds featuring a singly bonded Pd2(6+) core.
• To investigate the influence of ligand substituents on the stability and yield of these palladium complexes.
• To characterize the electronic configuration and structural properties of the synthesized compounds.

Main Methods:

• General synthesis of dipalladium compounds with the formula R,S-cis-Pd2(C6H4PPh2)2(O2CR)2Cl2.
• Variation of the alkyl group (R) in the carboxylate ligands to study electronic effects.
• X-ray crystallography to determine Pd-Pd bond distances.
• Density Functional Theory (DFT) calculations to elucidate electronic configuration.

Main Results:

• A general method for synthesizing dipalladium compounds with a singly bonded Pd2(6+) core was successfully developed.
• Compounds exhibited high stability and yields when electron-donating groups were present on the carboxylate ligands.
• Specific Pd-Pd distances were determined for diamagnetic compounds (e.g., 2.5434(4) Å for R=CF3, 2.5241(9) Å for R=CMe3).
• DFT calculations indicated an electronic configuration of sigma2pi4delta2delta*2pi*4.

Conclusions:

• The study presents rare examples of stable palladium(III) compounds.
• The developed synthetic method offers a pathway to novel palladium cluster compounds.
• The findings contribute to the understanding of metal-metal bonding and electronic structures in low-valent palladium complexes.