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

The structure of 1-chlorosilatrane was studied using gas-phase electron diffraction (GED). Compared to 1-fluorosilatrane, 1-chlorosilatrane has a shorter coordination Si←N bond in the gas phase. This result shows that the Si←N bond length in 1-halosilatranes decreases when the halogen is replaced by an atom that forms a weaker bond with Si, rather than by a more electronegative atom. This observation supports the applicability of the three-center four-electron model to describe bonding in these compounds. A significant anharmonicity effect on the structure of 1-chlorosilatrane was also detected in the GED experiment. Theoretical modeling of the photoelectron spectrum (using CCSD(T), EOM-IP-CCSD, OVGF methods, as well as the linear vibronic coupling model) allowed for band assignment in the experimental photoelectron spectrum and facilitated the study of the valence electronic structure of 1-chlorosilatrane. Both orbital and quantum topological approaches indicate the presence of a covalent component in the Si···N interaction in this molecule.