High pressure crystal structure of nitroethane.

Area of Science:

• Materials Science
• Physical Chemistry
• Crystallography

Background:

• Nitroethane is a liquid at ambient conditions.
• Understanding its behavior under high pressure is crucial for materials science.
• Previous studies have investigated nitroethane's phase transitions.

Purpose of the Study:

• To investigate the high-pressure crystalline phases of nitroethane.
• To determine the structure of nitroethane at static high pressures.
• To compare experimental findings with theoretical predictions.

Main Methods:

• Diamond anvil cell technique for static high pressure compression.
• X-ray diffraction for phase identification and structural analysis.
• Density functional theory (DFT) calculations for structural prediction and enthalpy comparison.

Main Results:

• A liquid-solid transition was observed around 4.3-3.6 GPa, forming a monoclinic structure (P21).
• DFT calculations predicted the P21 monoclinic structure as the lowest enthalpy solution.
• Unit cell volumes showed deviations from DFT predictions under non-hydrostatic conditions, with evidence of intermolecular hydrogen bonding.

Conclusions:

• The monoclinic P21 structure is the stable crystalline phase of nitroethane at high pressures.
• Non-hydrostatic conditions and intermolecular hydrogen bonding influence the observed phase transitions and structural parameters.
• Experimental results are in good agreement with DFT predictions, validating the theoretical approach.