One-dimensional anionic radical chains based on M₂P₂ rings (M = Ti, Zr, Hf)

Area of Science:

• Organometallic Chemistry
• Polymer Chemistry
• Materials Science

Background:

• Metallocene complexes are versatile precursors in coordination chemistry.
• Phosphorus-based radical species are of significant interest due to their unique electronic properties.
• Development of novel radical coordination polymers remains a key area in materials science.

Purpose of the Study:

• To synthesize and characterize novel metallocene-phosphorus based radical coordination polymers.
• To investigate the structural and electronic properties of these new materials.
• To explore the potential for chain cleavage into monomeric complexes.

Main Methods:

• Single-step synthesis involving group 4 metallocene dichlorides, pentaphosphaferrocene, and potassium metal.
• Characterization using Electron Paramagnetic Resonance (EPR) and X-ray Absorption Near Edge Structure (XANES) spectroscopy.
• Theoretical validation through quantum chemical calculations.

Main Results:

• Successfully synthesized radical polymeric chains with the formula [K{Cp2M}2{(η4-P5)FeCp*}2]n (M = Ti, Zr, Hf).
• Identified a novel four-membered P2M2 core, exhibiting a radical anionic nature.
• Demonstrated chain cleavage into charge-separated monomeric complexes upon reaction with [2.2.2]-cryptand.

Conclusions:

• The study presents a new class of metallocene-phosphorus based radical coordination polymers.
• The P2M2 core represents a rare example of a main group element-based radical polymeric chain.
• The synthesized polymers can be controllably cleaved into monomeric units, offering potential for further functionalization.