Electron-Transfer-Induced Structural Modification in a Thermochromic Hofmann Clathrate Derivative

Area of Science:

• Coordination Chemistry
• Materials Science
• Solid-State Chemistry

Background:

• Hofmann-type clathrates are coordination compounds with diverse applications.
• Electron transfer (ET) mechanisms in molecular materials are crucial for device functionality.
• Understanding temperature-dependent phenomena in clathrates is key to their technological exploitation.

Purpose of the Study:

• To synthesize and characterize a novel Hofmann-type clathrate with potential for unique electronic properties.
• To investigate the mechanism of thermally activated electron transfer (ET) in the absence of spin crossover.
• To correlate structural dynamics with observed thermochromic behavior.

Main Methods:

• Single-crystal and powder X-ray diffraction for structural analysis at varying temperatures.
• Infrared (IR) spectroscopy to probe electronic interactions and bonding.
• Thermal analysis to study temperature-dependent phase transitions.

Main Results:

• A Hofmann-type clathrate, {Fe2(2,4-(OCH3)2-pbpy)2(H2O)2[μ2-Pt(CN)4][μ3-Pt(CN)4]2·4H2O}, was synthesized and characterized.
• Thermally activated electron transfer (ET) was observed without spin crossover, linked to structural rearrangements.
• A thermochromic hysteretic transition from yellow to orange was identified, correlating with iron coordination sphere changes.

Conclusions:

• The study elucidates a novel ET mechanism in Hofmann-type clathrates driven by structural dynamics.
• Nonbridging cyanide moieties and bipyridinium units play key roles in the electron transfer process.
• This research contributes to a deeper understanding of structure-property relationships in molecular materials.