Neutral and Anionic Square Planar Palladium(0) Complexes Stabilized by a Silicon Z-Type Ligand

Area of Science:

• Organometallic Chemistry
• Catalysis
• Coordination Chemistry

Background:

• Anionic [Pd(0)-X]⁻ ate complexes are proposed intermediates in palladium-catalyzed cross-coupling.
• Isolation of these complexes has been historically challenging.

Purpose of the Study:

• To synthesize and characterize the first anionic [Pd(0)-X]⁻ ate complex.
• To investigate the coordination behavior and electronic structure of these novel complexes.
• To explore their potential role in catalytic oxidative addition reactions.

Main Methods:

• Synthesis of anionic [Pd(0)-X]⁻ ate complexes using a chelating Lewis acidic bis(amidophenolato)silane Z-type ligand.
• X-ray crystallography to determine coordination geometry.
• Theoretical calculations (e.g., DFT) to analyze electronic structure and bonding.
• Reactivity studies to probe catalytic potential.

Main Results:

• Successful isolation and characterization of the first anionic [Pd(0)-X]⁻ ate complexes.
• Observation of unusual square planar coordination for a d¹⁰ metal center in these complexes.
• Theoretical analysis revealed interactions between the Lewis acidic silicon center and palladium.
• Reactivity studies indicated potential roles for anionic additives in oxidative addition.

Conclusions:

• The development of a strong Z-type ligand enabled the isolation of previously elusive anionic palladium(0) ate complexes.
• These complexes exhibit unique coordination properties and offer new avenues for understanding palladium catalysis.
• Further research into their reactivity could lead to advancements in cross-coupling methodologies.