Mono-β-diketonate Metal Complexes of the First Transition Series

Area of Science:

• Organometallic Chemistry
• Catalysis
• Ligand Design

Background:

• Mono-β-diketonate compounds are crucial in base metal catalysis but difficult to isolate.
• Existing acac-type ligands have synthetic and structural limitations.
• The NacNac ligand platform emerged as an alternative.

Purpose of the Study:

• To synthesize a novel β-diketone ligand for kinetically stabilizing catalytic intermediates.
• To explore the utility of this ligand in base metal catalysis.
• To develop new precatalysts for reactions involving first-row transition metals.

Main Methods:

• Synthesis of a novel β-diketone using acyl triflate and lithium enolate.
• Preparation of transmetalation salts.
• Transmetalation reactions with Fe(II), Co(II), Ni(II), Cu(I), and Cu(II) compounds.
• Characterization using single-crystal X-ray diffraction (XRD), IR, UV-vis, NMR, and HRMS.
• Density Functional Theory (DFT) calculations.

Main Results:

• Successful synthesis of a β-diketone ligand and its metal complexes.
• Isolation and structural characterization of a dozen compounds, mostly bridged dimers.
• Demonstration of compounds as effective precatalysts in base metal catalysis.
• Validation of DFT for predicting structures and mechanisms.
• Reactivity studies with small molecules and solvents.

Conclusions:

• The developed β-diketone ligand effectively stabilizes catalytic intermediates.
• The new compounds serve as versatile precatalysts for base metal catalysis.
• Bis(2,6-dimesitylbenzoyl)methane (L) is a valuable ligand for future catalyst development.