Crystal structure and dynamics of Mg(ND3)6Cl2.

Area of Science:

• Solid-state chemistry
• Materials science
• Crystallography

Background:

• Magnesium hexammine chloride deuteride (Mg(ND(3))(6)Cl(2)) presents a unique system for studying molecular dynamics within a crystal lattice.
• Understanding the interplay between molecular symmetry and observed crystallographic symmetry is crucial for accurate structural determination.

Purpose of the Study:

• To elucidate the crystal structure and dynamics of Mg(ND(3))(6)Cl(2).
• To reconcile the apparent symmetry observed in diffraction data with the intrinsic symmetry of the ND(3) molecule.

Main Methods:

• Powder neutron diffraction was employed to collect structural data.
• Molecular dynamics simulations were performed to model the behavior of ND(3) molecules.

Main Results:

• Diffraction data initially suggested a square arrangement of deuterium sites, inconsistent with ND(3) symmetry.
• Molecular dynamics revealed correlated rotational and translational motion of ND(3) molecules.
• A disordered structure model, incorporating molecular dynamics findings, provided a better fit to experimental data and aligned with ND(3) 3-fold symmetry.

Conclusions:

• The observed crystal structure is a result of dynamic molecular motion, not static arrangement.
• Molecular dynamics simulations are essential for interpreting complex crystallographic data in systems with mobile molecular units.
• A more accurate structural model for Mg(ND(3))(6)Cl(2) has been established, respecting molecular symmetry.