Aryl-Aryl Interactions in (Aryl-Perhalogenated) 1,2-Diaryldisilanes

Area of Science:

• Organosilicon Chemistry
• Supramolecular Chemistry
• Computational Chemistry

Background:

• 1,2-diaryltetramethyldisilanes are compounds with potential applications in materials science.
• Understanding non-covalent interactions, such as London dispersion forces, is crucial for predicting molecular behavior and designing new materials.
• Aryl-aryl interactions play a significant role in the solid-state and gas-phase structures of organic and organometallic compounds.

Purpose of the Study:

• To investigate the impact of aryl group substitution on the structure and conformation of 1,2-diaryltetramethyldisilanes.
• To elucidate the role of London dispersion forces in mediating aryl-aryl interactions within these molecules.
• To compare the solid-state and gas-phase structures and analyze the intramolecular interactions.

Main Methods:

• Synthesis of 1,2-diaryltetramethyldisilanes via salt elimination from 1,2-dichlorotetramethyldisilane.
• Solid-state structure determination using X-ray diffraction.
• Gas-phase structure determination using gas electron diffraction.
• Computational analysis of interaction energies using SAPT (Symmetry-Adapted Perturbation Theory) calculations.

Main Results:

• The solid-state structures of fluorinated and chlorinated derivatives are dominated by aryl-aryl interactions.
• The perchlorinated derivative (Cl5C6-(SiMe2)2-C6Cl5) exclusively adopts an eclipsed syn-conformer in the gas phase, featuring distorted Si-C6Cl5 units due to strong intramolecular interactions.
• The perfluorinated derivative (F5C6-(SiMe2)2-C6F5) exhibits weaker intramolecular interactions compared to its chlorinated counterpart.

Conclusions:

• London dispersion forces are a key factor governing the conformational preferences of diaryltetramethyldisilanes, particularly in highly halogenated systems.
• Significant intramolecular interactions can lead to unexpected conformational behavior in the gas phase, deviating from typical packing in the solid state.
• The interplay between intermolecular and intramolecular forces dictates the overall molecular architecture and properties of these organosilicon compounds.