Silylene-Functionalized N-Heterocyclic Carbene (Si-NHC)

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• N-Heterocyclic Carbene Chemistry

Background:

• N-heterocyclic carbenes (NHCs) are versatile ligands in organometallic chemistry.
• Silylenes, silicon analogs of carbenes, are reactive species with unique electronic properties.
• The combination of silylene and NHC functionalities in a single molecule presents an exciting frontier in chemistry.

Purpose of the Study:

• To synthesize and characterize the first silylene-functionalized N-heterocyclic carbene (Si-NHC).
• To investigate the electronic structure and bonding of the novel Si-NHC.
• To explore the reactivity of the Si-NHC with chalcogens, silicon halides, and metal precursors.

Main Methods:

• Synthesis of the Si-NHC via reaction of a monochlorosilylene with a ditopic carbanionic-NHC.
• Spectroscopic and structural characterization of the synthesized compounds.
• Computational studies to determine the electronic structure (HOMO, HOMO-1).
• Reactivity studies involving chalcogens, silicon halides, and an iridium complex.

Main Results:

• The first silylene-functionalized N-heterocyclic carbene, {(L 1 )Si}(L 2 ), was successfully synthesized.
• The electronic structure reveals the HOMO is primarily localized on the silylene lone pair.
• Reactions with sulfur, selenium, and tellurium yielded novel heavier ketone derivatives with polarized Si-E bonds.
• The Si-NHC acted as a reducing agent, leading to disproportionation of Si 2 Cl 6 .
• Formation of silyl-functionalized NHC, imidazolium salt, and an iridium-silylene complex was achieved.

Conclusions:

• The synthesized Si-NHC is a stable, reactive species with a unique electronic configuration.
• The Si-NHC can be functionalized at both the silylene and carbene centers.
• This work expands the scope of NHC chemistry and provides a new platform for exploring silicon-based materials and catalysts.