Structural Characterization of a Boron(III) η²-σ-Silane-Complex

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Chemical Synthesis

Background:

• H-E bond activations are vital in chemical transformations.
• η²-σ-complexes are key intermediates, but those with d⁰ metals or high-oxidation-state main group elements are elusive.
• Previous σ-(H-Si)-complexes relied on back-donation for stability.

Purpose of the Study:

• To synthesize and characterize novel σ-complexes involving d⁰ metals or high-oxidation-state main group elements.
• To investigate the bonding and stability of a silane-borenium complex.
• To explore new pathways for σ-bond activation and metathesis.

Main Methods:

• Synthesis of an o-carboranyl-substituted hydroborenium.
• Formation and isolation of its η²-σ-(H-Si)-complex.
• X-ray crystallographic analysis.
• Computational studies (DFT).

Main Results:

• Successful synthesis and X-ray characterization of a unique η²-σ-(H-Si)-complex.
• Computational analysis revealed no significant back-donation from silane to borenium.
• Stability is attributed to σ-orbital interaction and steric factors.

Conclusions:

• This study reports the first structurally characterized silane-borenium complex of this type.
• The findings challenge previous assumptions about the stabilizing mechanisms in σ-complexes.
• Provides new insights into σ-bond activation mechanisms involving electrophilic main group elements.