Dinuclear lanthanide complexes with chalcogene-pnictogene cluster bridging ligands as precursors for magnetic materials

• Applicant: Dr. Svetlana Klementeva
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 516863633

In recent years, coordination chemistry of rare earths with heavy p-block elements has gained significant attention. Novel reactivity and beautiful structural properties have been developed, including the activation of elemental pnictogens and chalcogens and related inorganic substrates by low-valent lanthanides, showing an arising interest in this field. The extension of this chemistry to lanthanides of relevance to single-molecule magnetism is an enticing prospect. The soft ligands based on the heavy pnictogen- and chalcogene-donors could be a significant advantage for SMM properties offer a more efficient coupling route for the exchange interaction between paramagnetic centers. In addition, there is merit in exploring soft ligand environments since crystal field effects are the main interactions that lead to slowly relaxing magnetization in lanthanide-based SMMs. The main goal of the project is to develop new classes of dinuclear lanthanide complexes with bridging ligands containing heavy 14-16 group elements in attempt to find promising applications for design of high-performance SMMs. For the preparation of compounds with cluster inorganic core, an original synthetic approach will be explored. Lanthanide complexes with chalсogenide bridging ligands with a general formula [(L2Ln)2(μ-E)] and/or [(LLn)(μ-E)]2 (E = Se, Te) will be used as starting materials, and an insertion of various inorganic substrates into the Ln-E bond will be performed. A number of inorganic anhydrides and related compounds (As4O6, As4S6, As4S4, P4O6, P2S3, P2S5 etc.) will be used as inorganic substrates. Thus, the combination of a rare-earth element with inorganic chalcogenide-containing ligands will provide precursors that can be used in the design of new magnetic materials. The most ambitious step concerns in this respect the following one-electron reduction of these compounds in order enhance the exchange ferromagnetic interaction between magnetic centers. The presence of sterically hindered ligands (L - in general cyclopentadienyl with different substituents) will allow to obtain compounds soluble in organic solvents and to control the proper local symmetry of the lanthanide, which plays a key role in magnetic behavior. Both cyclopentadienyl ligands and cluster bridging blocks will impart strong axiality to the dinuclear lanthanide complexes, which might hence suppress the QTM. Noteworthy, the composition of the bridging ligands can vary over a wide range from the lighter oxygen, sulfur and phosphor to the heavier arsenic, selenium and tellurium. The detailed study of molecular and electronic structure of novel dinuclear dysprosium complexes with cluster ligands, as well as DC and AC magnetic measurements will be carried out.

• DFG Programme: Research Grants