Ferrocenyl-based di- and trinuclear lanthanide complexes: solid state structures, (spectro)electrochemical and DFT...

Area of Science:

• Coordination Chemistry
• Organometallic Chemistry
• Materials Science

Background:

• Lanthanide complexes with ferrocenylcarboxylato ligands are of interest for their unique structural and electronic properties.
• Understanding the relationship between structure, coordination modes, and electrochemical behavior is crucial for designing new functional materials.

Purpose of the Study:

• To synthesize and characterize novel dinuclear and trinuclear ferrocenylcarboxylato-bridged lanthanide complexes.
• To investigate the structural features, coordination chemistry, and electrochemical properties of these new complexes.
• To elucidate the factors governing the redox behavior of the ferrocenylcarboxylato ligands within these lanthanide frameworks.

Main Methods:

• Synthesis of dinuclear and trinuclear lanthanide complexes using lanthanide chlorides and ferrocenylcarboxylic acid.
• Single crystal X-ray structure determination to elucidate molecular structures and coordination modes.
• Infrared (IR) spectroscopy to confirm structural motifs.
• Electrochemical studies including cyclic voltammetry (CV) and square-wave voltammetry (SWV).
• UV-Vis/NIR spectroelectrochemical measurements.
• Density Functional Theory (DFT) calculations.

Main Results:

• Successful synthesis of dinuclear [Ln(μO:κ2OO'-O2CFc)(O2CFc)2(H2O)(dmf)]2·(dmf)2 and trinuclear [Bu4N][Ln3(μ-O2CFc)3(μO:κ2OO'-O2CFc)3(O2CFc)3(μ3-OH)]·[Bu4N]Cl complexes.
• X-ray crystallography revealed intricate bridging of lanthanide ions by ferrocenylcarboxylato units and specific coordination numbers and geometries.
• Electrochemical studies showed superimposed redox events for dinuclear complexes and three distinct events for trinuclear complexes, with redox behavior correlating to mononuclear analogues.
• Spectroelectrochemical measurements indicated no electron transfer between ferrocenyl units or lanthanides in the trinuclear terbium complex.
• DFT calculations highlighted the importance of spatial distance over binding mode in determining the order of redox events in trinuclear complexes.

Conclusions:

• The study successfully synthesized and characterized novel ferrocenylcarboxylato-bridged dinuclear and trinuclear lanthanide complexes.
• The structural diversity and coordination modes significantly influence the electrochemical properties of these complexes.
• Redox behavior in trinuclear complexes is primarily governed by the spatial arrangement of ferrocenyl units, as supported by DFT calculations.