IPr3 Si3 Cl5 (+) : A Highly Reactive Cation with Silanide Character

Area of Science:

• Organosilicon Chemistry
• Main Group Chemistry
• Carbene Chemistry

Background:

• Metastable silicon dichloride (SiCl2) is a reactive precursor in silicon chemistry.
• N,N-diisopropylimidazo-2-ylidene (IPr) is a sterically accessible N-heterocyclic carbene ligand.

Purpose of the Study:

• To synthesize and characterize novel silicon-containing cations.
• To investigate the reactivity and electronic structure of polysilicon species.

Main Methods:

• Reaction of metastable SiCl2 with IPr carbene.
• Dehalogenation using trimethylsilyl triflate (Me3SiOTf).
• Quantum chemical calculations (DFT).
• Nuclear Magnetic Resonance (NMR) spectroscopy.

Main Results:

• Synthesis of the silyl cation salt [(IPr3 Si3 Cl5 )](+) Cl(-) (1-Cl) featuring a Si3 backbone.
• Conversion of 1-Cl to the dicationic silyl halide [(IPr3 Si3 Cl4 )](2+) (2) via dehalogenation.
• Computational and NMR studies indicate significant negative charge localization on the central silicon atom, suggesting silanide character.

Conclusions:

• The synthesized silicon cations exhibit silanide-like properties due to charge localization.
• These findings expand the understanding of bonding and reactivity in silicon cluster compounds.