One-Dimensional Diiodine-Iodobismuthate(III) Hybrids Cat₃{[Bi₂I₉](I₂)₃}: Syntheses, Stability, and Optical Properties

Area of Science:

• Inorganic Chemistry
• Materials Science
• Solid-State Chemistry

Background:

• Polyhalogen-halometalates are compounds containing halogen atoms and metal halides.
• Iodine-rich compounds are of interest for their unique electronic and optical properties.
• Diiodine (I2) units can be incorporated into metal-halide frameworks, influencing their characteristics.

Purpose of the Study:

• To synthesize and characterize novel one-dimensional iodine-rich iodobismuthates(III).
• To investigate the structural features, particularly the "trapped" diiodine units.
• To determine the optical and thermal properties of the synthesized compounds.

Main Methods:

• Single-crystal X-ray diffraction for structural analysis.
• UV-Vis spectroscopy for optical band gap determination.
• Thermogravimetric analysis for thermal stability assessment.

Main Results:

• Synthesis of two new one-dimensional iodobismuthates(III) with the formula Cat3{[Bi2I9](I2)3}.
• These compounds exhibit the highest content of "trapped" diiodine units reported for p-block polyhalogen-halometalates.
• Observed narrow optical band gaps of 1.55 eV for complex 1 (Cat = 1,4-MePy) and 1.63 eV for complex 2 (Cat = 1-EtBMAP).
• Moderate thermal stability was confirmed for both complexes.

Conclusions:

• The synthesized iodobismuthates(III) represent a new class of iodine-rich materials.
• The high loading of diiodine units significantly influences the electronic and optical properties.
• These materials show promise for applications requiring narrow band gap semiconductors.