Lanthanide Squarate Complexes Containing Mono- and Trivalent Thallium

Area of Science:

• Inorganic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Lanthanide complexes with squarate ligands are of interest due to their diverse structures and properties.
• Thallium, particularly in its trivalent state, presents unique challenges in complex formation.
• Understanding the coordination behavior of squarate and oxalate ligands is crucial for designing novel materials.

Purpose of the Study:

• To synthesize and structurally characterize new thallium lanthanide squarate complexes.
• To investigate the formation of unusual oxidation states, such as trivalent thallium, in these complexes.
• To explore the co-ligand behavior of squarate and oxalate in cerium complexes.

Main Methods:

• Synthesis of novel thallium lanthanide squarate and cerium squarate oxalate complexes.
• Single-crystal X-ray diffraction for detailed structural elucidation.
• In situ oxidation reactions to achieve unusual oxidation states.

Main Results:

• 17 new complexes were synthesized, including 16 thallium lanthanide squarates and 1 cerium squarate oxalate.
• Complexes exhibit varying coordination modes and denticities of the squarate ligand.
• Trivalent thallium was stabilized via in situ oxidation by tetravalent cerium.
• Complexes display diverse structural architectures: 2D layers, 1D chains, and 3D frameworks.
• Rare coordination modes for the squarate ligand were observed in two complexes.

Conclusions:

• The study successfully synthesized and characterized novel thallium lanthanide squarate complexes, expanding the known library of these compounds.
• The stabilization of trivalent thallium highlights a novel synthetic strategy and expands understanding of thallium's coordination chemistry.
• The structural diversity, including 2D, 1D, and 3D arrangements, and the observation of rare squarate coordination modes, offer insights into lanthanide-ligand interactions.