Polyoxometalate-Dicarboxylate Hybrid Dimers with {SiW₁₀Cr₂} Nodes: Syntheses, Structures, and Mass Spectrometric...

Area of Science:

• Inorganic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Polyoxometalates (POMs) are versatile inorganic clusters with tunable properties.
• Hybrid materials combining POMs with organic linkers offer unique structural and functional possibilities.
• Dichromium-substituted silicodecatungstates ({SiW₁₀Cr₂}) represent a specific class of POMs with potential for novel hybrid assembly.

Purpose of the Study:

• To synthesize and characterize a new family of polyoxometalate-organic hybrid compounds.
• To investigate the self-assembly behavior of {SiW₁₀Cr₂} clusters with flexible dicarboxylate ligands.
• To explore the structural motifs and stability of the resulting hybrid dimers.

Main Methods:

• Synthesis of hybrid compounds using {SiW₁₀Cr₂} secondary building blocks and dicarboxylate ligands.
• Single-crystal X-ray diffraction for detailed structural elucidation.
• Electrospray Ionization Mass Spectrometry (ESI-MS) for characterization of paramagnetic and NMR-unfriendly species.

Main Results:

• Five novel polyoxometalate-organic hybrid compounds were successfully synthesized.
• All compounds exhibited a cyclic dimer motif, comprising two {SiW₁₀Cr₂} clusters linked by dicarboxylates.
• This cyclic structure represents the minimum cluster requirement for a closed loop, driven by entropic favorability.
• The kinetic inertness of the Cr³⁺-based hybrid dimers was confirmed.

Conclusions:

• A new family of entropically favored, cyclic hybrid dimers based on {SiW₁₀Cr₂} has been developed.
• The study highlights the utility of ESI-MS for characterizing kinetically inert, paramagnetic POM-organic hybrids.
• The findings contribute to the understanding of self-assembly principles in POM-based supramolecular chemistry.