Gradual solid-state redox-isomerism in the lanthanide series

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Lanthanide complexes exhibit diverse electronic properties.
• Redox-isomerism, or valence tautomerism, is a fascinating phenomenon in coordination compounds.
• Understanding electron transfer mechanisms is crucial for designing functional materials.

Purpose of the Study:

• To investigate the redox-isomerism in a novel ytterbium complex.
• To explore the influence of temperature and solvent on the electronic state of the complex.
• To compare the observed redox behavior with existing lanthanide systems.

Main Methods:

• Synthesis and characterization of the ytterbium complex [(Ar^BIG-bian)^2-Yb²⁺(dme)].
• Oxidation reaction with Me₂NC(S)S-S(S)CNMe₂ to form redox-isomers.
• Variable-temperature studies in solution and solid state using spectroscopic techniques.
• Comparison with a previously reported lanthanide complex exhibiting solid-state redox-isomerism.

Main Results:

• Formation of two redox-isomers, [(Ar^BIG-bian)^2-Yb³⁺{SC(S)NMe₂}^1-(dme)] and [(Ar^BIG-bian)^1-Yb²⁺{SC(S)NMe₂}^1-(dme)], in solution.
• Temperature-dependent electron transfer from Yb²⁺ to the Ar^BIG-bian radical-anion in the solid state, favoring the Yb³⁺ isomer at lower temperatures.
• Ratio of isomers changes from 1:1 at 350 K to 3:1 at 100 K.
• Contrast with a dimer complex where electron transfer occurs within a narrow temperature range.

Conclusions:

• The studied ytterbium complex exhibits temperature-dependent redox-isomerism.
• Solvent and temperature play critical roles in determining the isomer distribution.
• This work expands the understanding of valence tautomerism in lanthanide chemistry.
• Provides insights into the dynamic electronic behavior of organometallic compounds.