Synthesis and Characterisation of Phosphino-Aryloxide Rare Earth Complexes

Area of Science:

• Organometallic Chemistry
• Rare Earth Chemistry
• Ligand Design

Background:

• Rare earth (RE) elements offer unique electronic and steric properties for coordination chemistry.
• Phosphino-aryloxide ligands provide versatile coordination modes and tunable electronic environments.
• Frustrated Lewis pairs (FLPs) are reactive species capable of small molecule activation.

Purpose of the Study:

• To synthesize and characterize novel homoleptic rare earth complexes with phosphino-aryloxide ligands.
• To investigate the structural features and bonding interactions within the RE complexes.
• To explore the potential for frustrated Lewis pair (FLP) activity and reactivity with small molecules.

Main Methods:

• Synthesis of homoleptic rare earth complexes.
• Characterization using multinuclear NMR and IR spectroscopy.
• X-ray crystallography and elemental analysis for structural determination.

Main Results:

• Successful preparation and characterization of RE complexes (1-RE, 2-La) with phosphino-aryloxide ligands.
• Structural studies revealed varying RE-P interactions due to differences in Lewis acidity and ionic radii across the lanthanide series.
• Complexes showed potential for FLP-type activity, with reactivity observed towards small molecules like H2, CO, and CO2.
• Isolation and characterization of side-products (3-RE) involving phosphonium-aryloxide ligands.

Conclusions:

• The synthesized rare earth complexes exhibit diverse structural motifs and RE-P interactions.
• The observed structural characteristics suggest potential for frustrated Lewis pair (FLP) behavior.
• Reactivity studies indicate the capacity of these complexes to engage with small molecules, leading to novel ligand incorporation.