A stable silicon(0) compound with a Si=Si double bond

Area of Science:

• Inorganic Chemistry
• Organosilicon Chemistry
• Main Group Element Chemistry

Background:

• Dative ligand coordination is prevalent in transition metal chemistry.
• This bonding is infrequently observed in main group elements at the zero oxidation state.
• Hypervalent silicon-carbene complexes offer a platform for exploring novel bonding.

Purpose of the Study:

• To synthesize and characterize novel silicon compounds with unusual bonding.
• To investigate the formation of silicon-silicon multiple bonds in zero-valent main group compounds.
• To explore the stabilizing effect of carbenes on low-valent silicon species.

Main Methods:

• Potassium graphite reduction of a neutral hypervalent silicon-carbene complex (L:SiCl4).
• Synthesis of a carbene-stabilized bis-silylene (L:(Cl)Si-Si(Cl):L).
• Characterization of a carbene-stabilized diatomic silicon molecule (L:Si=Si:L) using X-ray diffraction and computational studies.

Main Results:

• Formation of L:(Cl)Si-Si(Cl):L, a carbene-stabilized bis-silylene.
• Isolation of L:Si=Si:L, a carbene-stabilized diatomic silicon molecule.
• The diatomic silicon molecule exhibits a silicon-silicon bond distance of 2.2294 ± 0.0011 Å, indicative of a Si=Si double bond.
• Computational studies confirmed the bonding nature in both products.

Conclusions:

• Demonstrated the synthesis of a diatomic silicon molecule with a formal zero oxidation state for silicon.
• Established the existence of a silicon-silicon double bond stabilized by a carbene ligand.
• Highlighted the potential of carbene ligands in stabilizing unusual bonding motifs in main group chemistry.