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Published on: October 10, 2016
On the structure of sulfur-stabilized allyllithium compounds in solution
1Institut fur Organische Chemie und Makromolekulare Chemie der Friedrich-Schiller-Universitat Jena, Humboldtstr. 10, D-07743 Jena, Germany.
The Journal of Organic Chemistry
|September 16, 2000
Summary
Sulfur-stabilized allyllithium compounds exist as monomers in THF. Their structures in solution change with sulfur oxidation state, revealing distinct lithium interactions and conformations.
Area of Science:
- Organometallic Chemistry
- Computational Chemistry
- Solution-State Structural Analysis
Background:
- Allyllithium compounds are key intermediates in organic synthesis.
- Understanding their solution-state structures is crucial for reactivity prediction.
- Sulfur substituents can influence the electronic and structural properties of organolithium species.
Purpose of the Study:
- To determine the solution-state structures of three sulfur-stabilized allyllithium compounds.
- To investigate the effect of sulfur oxidation state on allyllithium structure.
- To elucidate the nature of lithium interactions and conformations.
Main Methods:
- Density functional calculations (B3LYP/6-31+G(d)) were employed.
- Experimental validation using Nuclear Magnetic Resonance (NMR) spectroscopy.
- Cryoscopic measurements were utilized for solution characterization.
Main Results:
- All studied lithium species exist as monomers in THF, adopting an endo conformation.
- Increasing sulfur oxidation state (thiol, sulfoxide, sulfone) alters the allyllithium structure.
- Specific lithium interactions (C-Li, Li-O contacts) and equilibria were identified for each compound.
Conclusions:
- The sulfur substituent significantly influences the structure and bonding of allyllithium compounds in solution.
- Sulfoxide and sulfone derivatives exhibit complex equilibria and intramolecular Li-O contacts.
- Computational and experimental data provide a comprehensive understanding of these organosulfur lithium species.
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