N─H or O─H Bond Activation With a Bicyclic Si₄ Ring Compound.

Area of Science:

• Organosilicon chemistry
• Inorganic chemistry
• Materials science

Background:

• The bicyclic silicon ring compound Si4{N(SiMe3)Mes}4 serves as a heavier analog to cyclobutadiene.
• Understanding the reactivity of such silicon clusters is crucial for developing new silicon-based materials and catalysts.

Purpose of the Study:

• To investigate the reaction pathways of Si4{N(SiMe3)Mes}4 with E-H bond containing compounds (E = N, O).
• To elucidate the mechanisms of E-H bond activation and functionalization in silicon ring systems.

Main Methods:

• Experimental reactions of Si4{N(SiMe3)Mes}4 with ammonia, water, methanol, ethanol, and phenol.
• Mechanistic calculations using density functional theory (DFT) to rationalize observed reactivity.

Main Results:

• Ammonia and water addition resulted in saturated Si4 rings with amine/hydride or hydroxyl/hydride functionalities, respectively.
• Reactions with methanol and ethanol yielded functionalized saturated Si4 rings and/or siliconoid clusters.
• Phenol addition led to a simple 1,3-addition product with minimal side products, indicating distinct reactivity compared to other alcohols.

Conclusions:

• The bicyclic silicon ring compound exhibits diverse reactivity towards E-H bond activation, leading to saturated and functionalized silicon rings.
• The reaction outcome is influenced by the nature of the E-H bond and the steric/electronic properties of the reacting molecule.
• DFT calculations provide valuable insights into the mechanistic pathways governing these transformations.