Weak Pnictogen Bond with Bismuth: Experimental Evidence Based on Bi-P Through-Space Coupling

Area of Science:

• Inorganic Chemistry
• Supramolecular Chemistry
• Chemical Physics

Background:

• Pnictogen bonding is a type of non-covalent interaction involving elements from Group 15.
• Understanding these interactions is crucial for designing novel materials and catalysts.
• Bismuth, a heavy pnictogen, offers unique electronic properties for such studies.

Purpose of the Study:

• To synthesize and characterize novel bismuth-containing molecular complexes.
• To investigate the nature and strength of pnictogen bonding involving bismuth.
• To explore the influence of halogen substituents on bismuth-pnictogen interactions.

Main Methods:

• Synthesis of [P(C6H4-o-CH2SCH3)3BiX3] complexes (X=Cl, Br, I).
• Characterization using single-crystal X-ray diffraction.
• Computational analysis including Density Functional Theory (DFT) and ab initio methods.
• Solid-state 31P Nuclear Magnetic Resonance (NMR) spectroscopy.

Main Results:

• Flexible, accordion-like molecular complexes were successfully synthesized.
• The strength of the Bi-P interaction is significantly influenced by the halogen substituent on bismuth.
• Unprecedented through-space 209Bi-31P coupling (J=2560 Hz) was observed in 31P NMR spectra.
• Experimental and computational data confirmed the predominantly electrostatic nature of the interaction.

Conclusions:

• The study provides direct evidence and quantification of pnictogen bonding involving bismuth.
• Halogen substituents play a critical role in modulating the strength of bismuth-pnictogen interactions.
• The observed 209Bi-31P coupling offers a novel spectroscopic handle for studying these interactions.