A Ketimide-Stabilized Palladium Nanocluster with a Hexagonal Aromatic Pd₇ Core

Area of Science:

• Inorganic Chemistry
• Materials Science
• Nanotechnology

Background:

• Palladium complexes are crucial in catalysis, but novel structures with unique electronic properties are continuously sought.
• The development of metal nanoclusters with aromatic characteristics offers new avenues in materials science and catalysis.

Purpose of the Study:

• To synthesize and characterize a novel mixed-valent palladium-7 (Pd7) nanosheet stabilized by ketimide ligands.
• To investigate the electronic properties, including aromaticity, of the synthesized Pd7 nanocluster.
• To explore the potential catalytic applications of the Pd7 nanosheet.

Main Methods:

• Synthesis of the Pd7 nanosheet, [Pd7(N═C(tBu)2)6], via the reaction of PdCl2(PhCN)2 and Li(N═C(tBu)2).
• Characterization using spectroscopic techniques (e.g., NMR) and density functional theory (DFT) calculations.
• Reaction of the Pd7 nanosheet with triphenylphosphine (Ph3P) to form a Pd(0) phosphine complex.

Main Results:

• Successful synthesis and characterization of the mixed-valent Pd7 nanosheet, [Pd7(N═C(tBu)2)6] (1), featuring a hexagonal planar [Pd7]6+ core.
• DFT calculations confirmed that Pd7 nanosheet (1) is an all-metal aromatic nanocluster with hexagonal symmetry and a significant diatropic ring-current.
• The Pd7 nanosheet (1) reacts with Ph3P to form Pd(PPh3)3 (3), indicating its potential as a precatalyst.

Conclusions:

• The synthesized Pd7 nanosheet represents a rare example of an all-metal aromatic nanocluster with potential catalytic applications.
• The ketimide ligands effectively stabilize the mixed-valent Pd7 core, imparting unique electronic and structural properties.
• The Pd7 nanosheet can serve as a valuable precatalyst for palladium-catalyzed cross-coupling reactions.