Monodentate σ-Accepting Boron-Based Ligands Bearing Square-Planar Ni(0) Centers

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Coordination Chemistry

Background:

• Transition metals act as electron donors to heavier group 13 elements (Al, Ga, In), termed Z-type ligands.
• Boron-based Z-type ligands typically require supporting coordination units for stability.
• Square-planar coordination geometry is traditionally linked to Ni(II) species.

Purpose of the Study:

• To synthesize and characterize novel square-planar Ni(0) complexes with monodentate Z-type boron ligands.
• To investigate the electronic and bonding characteristics of the Ni-B interaction.
• To explore a new strategy for stabilizing low-valent transition metal complexes.

Main Methods:

• Synthesis of nickel(0) complexes featuring tris(perfluoroaryl)boranes.
• Characterization using a combination of theoretical and experimental approaches.
• Utilizing frustrated L/Z-ligand pairs with sterically encumbered components.

Main Results:

• Successful synthesis of square-planar Ni(0) complexes with monodentate Z-type boron ligands.
• Experimental and theoretical evidence revealed a mixed covalent/dative character for the Ni-B bonds.
• Demonstrated the stabilization of low-valent transition metal species through frustrated ligand interactions.

Conclusions:

• The study presents a new method for synthesizing stable low-valent transition metal complexes with monodentate Z-type ligands.
• The findings challenge established ligand-field theory regarding coordination geometries.
• The frustrated L/Z-ligand strategy opens avenues for accessing unprecedented organometallic compounds.