Bond paths and van der Waals interactions in orpiment, As2S3

Area of Science:

• Solid-state chemistry
• Materials science
• Crystallography

Background:

• Orpiment (As(2)S(3)) is an inorganic molecular crystal with complex interlayer interactions.
• Understanding the nature of bonding in such materials is crucial for predicting their properties.
• Previous studies have utilized spectroscopic methods to probe interlayer interactions.

Purpose of the Study:

• To investigate the electron density distribution in orpiment.
• To correlate calculated electron density bond paths with experimentally observed interlayer bonded interactions.
• To provide evidence for the directional nature of van der Waals forces in inorganic molecular crystals.

Main Methods:

• Calculation of electron density distribution for orpiment.
• Combined infrared and Raman spectroscopy to detect experimental interlayer bonded interactions.
• Modeling of bond paths and interlayer interactions using a "key-lock" approach.

Main Results:

• Identified As-S, S-S, and As-As bond paths in the electron density distribution of orpiment.
• These calculated bond paths correlate with experimentally detected interlayer directed bonded interactions.
• Successful modeling of interlayer interactions supports the directional nature of van der Waals forces.

Conclusions:

• Electron density distribution analysis provides insights into interlayer bonding in orpiment.
• Experimental spectroscopic data (infrared and Raman) confirm the presence of directed interactions.
• The findings strongly support the hypothesis that van der Waals forces in inorganic molecular crystals are directional.