Carbene-Stabilized Dithiolene (L⁰ ) Zwitterions

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Supramolecular Chemistry

Background:

• Imidazole-based dithione dimers are versatile precursors in coordination chemistry.
• Lewis bases, including carbenes and silylenes, are known for their reactivity towards various substrates.
• Understanding the cleavage of sulfur-sulfur bonds is crucial for synthesizing novel organosulfur compounds.

Purpose of the Study:

• To investigate the reactions of an imidazole-based dithione dimer with different Lewis bases.
• To explore the synthesis of novel carbene-stabilized dithiolene zwitterions and silicon-dithiolene compounds.
• To characterize the bonding nature of the resulting products using experimental and theoretical methods.

Main Methods:

• Reaction of dithione dimer with cyclic(alkyl)(amino)carbene (CAAC).
• Reaction of dithione dimer with N-heterocyclic carbene (NHC).
• Reaction of dithione dimer with N-heterocyclic silylene (NHSi).
• Experimental characterization (e.g., NMR, X-ray crystallography) and theoretical calculations (e.g., DFT).

Main Results:

• CAAC and NHC successfully cleaved the S-S bonds in the dithione dimer, forming carbene-stabilized dithiolene zwitterions (3 and 5).
• NHSi also cleaved the S-S bonds, yielding a spirocyclic silicon-dithiolene compound (7).
• The bonding characteristics of the synthesized compounds were elucidated through comprehensive experimental and theoretical analyses.

Conclusions:

• Lewis bases, specifically CAAC, NHC, and NHSi, are effective in cleaving S-S bonds in imidazole-based dithione dimers.
• This study demonstrates a viable route to novel carbene-stabilized dithiolene zwitterions and silicon-dithiolene compounds.
• The investigation provides insights into the bonding and electronic structures of these unique organosulfur compounds.