Structures and Chemical Bonding in Antimony(III) Bromide Complexes with Pyridine

Area of Science:

• Solid-state chemistry
• Supramolecular chemistry
• Chemical bonding

Background:

• Weakly bonded molecules bridge chemical and van der Waals interactions.
• Understanding these interactions is crucial for materials science and drug design.

Purpose of the Study:

• To determine the molecular structures of six new antimony tribromide-pyridine complexes.
• To investigate the nature of antimony-bromine (Sb-Br) and antimony-nitrogen (Sb-N) interactions.
• To evaluate a new structural parameter for assessing bonding.

Main Methods:

• Single-crystal X-ray diffraction analysis.
• Density Functional Theory (DFT) calculations.
• Natural Bond Orbital (NBO) analysis, electrostatic potential analysis, and topological analysis.

Main Results:

• Six new SbBr3-Py complexes were structurally characterized.
• Sb atoms exhibited pseudo-octahedral coordination with additional Sb⋅⋅⋅Br contacts.
• Sb-Br interactions were classified as covalent or pnictogen bonds.
• A non-covalence criterion (NCC) was defined and correlated with bonding strength.

Conclusions:

• Sb-Br interactions exhibit diverse bonding characteristics, ranging from covalent to pnictogen bonds.
• The non-covalence criterion (NCC) provides a useful preliminary assessment of bonding situations in these complexes.
• This study enhances the understanding of weak interactions in antimony halide complexes.