Synthesis and Characterization of Phosphanophenolate-Based Rare-Earth Metal-Copper Complexes

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Rare-Earth Metal Complexes

Background:

• Rare-earth metal complexes with phosphine-phenolate ligands are of interest for their unique electronic and structural properties.
• Developing efficient synthetic routes to heterobimetallic complexes is crucial for exploring new materials and catalytic applications.

Purpose of the Study:

• To synthesize and characterize novel dinuclear rare-earth metal(III)-copper(I) complexes.
• To explore alternative synthetic strategies for heterobimetallic rare-earth metal-copper complexes.
• To investigate ligand exchange reactions on pre-formed dinuclear complexes.

Main Methods:

• Synthesis of dinuclear rare-earth metal(III)-copper(I) complexes via reaction of [Ln^III(OAr^P-κ²O,P)₃] with copper(I) triflate.
• Attempted synthesis of heterobimetallic complexes from a mononuclear copper complex and rare-earth metal amides.
• Triflate exchange reactions on dinuclear complexes using various nucleophiles, including alkaline metal amides, alkyls, and alkoxides.
• Characterization using NMR, UV-vis, IR spectroscopy, single-crystal X-ray diffraction, and elemental analysis.
• Magnetic moment determination using the Evans NMR method.

Main Results:

• Clean synthesis of dinuclear rare-earth metal(III)-copper(I) complexes [Ln^III(OTf)(μ-OAr^P-1κ¹O,2κ¹P)₃Cu^I] (2-Ln) was achieved.
• An alternative synthetic route starting from a mononuclear copper complex yielded heterobimetallic complexes in low yields with side-products.
• Triflate exchange was successful only with potassium tert-butoxide (KO^tBu), yielding [Ln^III(O^tBu)(μ-OAr^P-1κ¹O,2κ¹P)₃Cu^I] (4-Ln).
• Structural and spectroscopic data confirmed the formation and characterization of the new complexes.

Conclusions:

• The direct reaction of rare-earth metal complexes with copper(I) triflate is an efficient method for synthesizing dinuclear complexes.
• The explored alternative synthetic route is less favorable for generating heterobimetallic rare-earth metal-copper complexes.
• The tert-butoxide complexes (4-Ln) represent a new class of heterobimetallic compounds accessible via triflate exchange.