Azido-mediated intermolecular interactions of transition metal complexes

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Crystal Engineering

Background:

• The azido ligand (N3) is known for its versatile coordination chemistry.
• Understanding intermolecular interactions is crucial for predicting crystal packing and material properties.
• Mercury (Hg) complexes with fluorinated ligands offer unique electronic and structural characteristics.

Purpose of the Study:

• To computationally investigate the nature and strength of intermolecular contacts involving the azido ligand in [N3-Hg(CF3)] dimers.
• To analyze the role of different interactions, including N⋯N and Hg⋯N contacts, in stabilizing the crystal structure.
• To elucidate the energetic contributions and electronic factors governing these intermolecular associations.

Main Methods:

• Molecular electrostatic potential (MEP) mapping of the monomer.
• Energy Decomposition Analysis (EDA) to quantify interaction energies.
• Atoms in Molecules (AIM) topological analysis of electron density.
• Non-Covalent Interaction (NCI) isosurface analysis.

Main Results:

• Weakly stabilizing N⋯N contacts (0.2–2.7 kcal mol⁻¹) were identified between azido ligands.
• Dispersion forces play a significant role alongside electrostatic and orbital contributions in N⋯N interactions.
• Secondary Hg⋯N interactions contribute approximately -1 kcal mol⁻¹ stabilization.
• The monomer exhibits the ability to engage in multiple simultaneous intermolecular interactions within the crystal lattice.

Conclusions:

• Intermolecular azido-azido interactions are weak but significant, influenced by crystal topology.
• The combination of N⋯N and Hg⋯N interactions dictates the overall stability and packing of [N3-Hg(CF3)] complexes.
• Computational methods provide valuable insights into the subtle forces governing crystal structures of coordination compounds.