Gas-Phase Molecular Structure of 1-Chlorosilatrane: Electron Diffraction Study and Assignment of Photoelectron...

Area of Science:

• Organosilicon chemistry
• Structural chemistry
• Computational chemistry

Background:

• Silatranes are organosilicon compounds with a unique cage-like structure.
• The Si←N coordination bond is a key feature influencing silatrane properties.
• Understanding structure-bonding relationships in silatranes is crucial for predicting their reactivity.

Purpose of the Study:

• To determine the gas-phase structure of 1-chlorosilatrane using gas-phase electron diffraction (GED).
• To investigate the effect of halogen substitution on the Si←N bond length in 1-halosilatranes.
• To elucidate the valence electronic structure and bonding characteristics of 1-chlorosilatrane through theoretical modeling.

Main Methods:

• Gas-phase electron diffraction (GED) for structural determination.
• High-level computational methods (CCSD(T), EOM-IP-CCSD, OVGF) for electronic structure calculations.
• Linear vibronic coupling model for photoelectron spectroscopy analysis.
• Quantum topological methods to analyze bonding.

Main Results:

• 1-chlorosilatrane exhibits a shorter Si←N coordination bond in the gas phase compared to 1-fluorosilatrane.
• The Si←N bond length decreases as the Si-halogen bond strength weakens, supporting the three-center four-electron bonding model.
• Significant anharmonicity effects were observed in the GED experiment.
• Theoretical modeling enabled assignment of the photoelectron spectrum and revealed a covalent component in the Si···N interaction.

Conclusions:

• The Si←N bond length in 1-halosilatranes is inversely related to the strength of the Si-halogen bond.
• The three-center four-electron model effectively describes bonding in these systems.
• The Si←N interaction possesses a covalent character, influencing the overall molecular structure and electronic properties.