Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of Chalcogenidoplumbates(II or IV)

Area of Science:

• Solid-state chemistry and inorganic synthesis.
• Coordination chemistry of chalcogenide anions.
• Materials science of lead and transition metal compounds.

Background:

• Traditional lead chemistry primarily involves Pb(II) oxidation states.
• Synthesis of complex chalcogenide anions and clusters remains challenging.
• Understanding redox potentials is crucial for predicting compound stability.

Purpose of the Study:

• To explore novel solid-state and solvothermal synthetic routes for lead chalcogenides.
• To synthesize and characterize new chalcogenidoplumbate(II) and lead(IV) compounds.
• To investigate the formation of transition metal chalcogenide clusters and anions.

Main Methods:

• Solid-state synthesis via elemental fusion under inert conditions.
• Reduction of lead chalcogenide phases using alkaline metals in amines.
• Solvothermal treatment and reactions with transition metal compounds.
• Characterization using single-crystal X-ray diffraction and elemental analysis.
• Spectroscopic analysis (NMR) and quantum chemical calculations (DFT).

Main Results:

• Successful synthesis of Pb(II) chalcogenidoplumbate(II) salts with [PbTe3]2- or [Pb2Ch3]2- anions.
• Discovery of the first non-oxide/halide inorganic lead(IV) compound, [PbSe4]4-, via solid-state and solvothermal methods.
• Formation of transition metal chalcogenide clusters, including a µ-PbSe ligand, and binary anions like [HgTe2]2- and [BiSe3]3-.
• DFT calculations provided insights into electronic configurations, bonding, and stability of the synthesized compounds.
• Demonstrated delocalized mixed valence in Rh-containing compounds and electron-precise nature in Pd-containing anions.

Conclusions:

• Novel synthetic strategies enable access to diverse lead chalcogenide anions and clusters.
• The unexpected stability of Pb(IV) in the [PbSe4]4- anion is attributed to crystal lattice stabilization.
• The developed methods are applicable to other elemental combinations, facilitating the synthesis of new inorganic materials.