Mass Spectrometric Studies of Reductive Elimination from Si(IV) Anions

Area of Science:

• Organometallic Chemistry
• Catalysis
• Main-Group Chemistry

Background:

• Reductive elimination (RE) is a critical step in many catalytic cycles but remains a significant challenge for main-group elements.
• Developing efficient main-group catalysts for bond coupling requires overcoming limitations in conventional oxidative addition/reductive elimination pathways.

Purpose of the Study:

• To demonstrate and characterize reductive elimination from silicon(IV) to silicon(II) in anionic hydrosilicates.
• To investigate the mechanism and factors influencing reductive elimination in main-group systems.

Main Methods:

• Electrospray ionisation mass spectrometry (ESI-MS) was used to study anionic Si(IV) hydrosilicates generated in solution.
• Density Functional Theory (DFT) calculations were employed to support experimental observations and elucidate the reaction mechanism.

Main Results:

• Direct observation of reductive elimination from anionic Si(IV) hydrosilicates to a Si(II) center was achieved.
• The activation energy for RE was found to decrease linearly with increasing electron-withdrawing character of aryl substituents.
• DFT studies supported an ionic mechanism involving an ion/molecule complex in the rate-limiting step.

Conclusions:

• This work presents a rare example of direct observation of reductive elimination from Si(IV) to Si(II), particularly involving anionic species.
• The findings provide valuable insights into the mechanism of reductive elimination in main-group chemistry, paving the way for novel catalyst design.