Solid-State Reactions of Eicosaborate [B₂₀ H₁₈ ]^2- Salts and Complexes

Area of Science:

• Inorganic Chemistry
• Solid-State Chemistry
• Boron Cluster Chemistry

Background:

• Octadecahydro-eicosaborate [B20H18]2- dianion exists as trans- and iso-isomers.
• Boron clusters can act as ligands in coordination chemistry.
• Understanding isomerization mechanisms in solid-state is crucial for materials science.

Purpose of the Study:

• To synthesize and characterize trans- and iso-isomers of [B20H18]2-.
• To investigate the ligand behavior of these isomers with transition metals.
• To study solid-state isomerization reactions and identify factors influencing them.

Main Methods:

• Fourier-transform infrared (FTIR) spectroscopy
• Boron-11 Nuclear Magnetic Resonance (11B NMR) spectroscopy
• X-ray diffraction (XRD) techniques
• In situ single-crystal X-ray diffraction

Main Results:

• Synthesis and characterization of trans- and iso-[B20H18]2- salts and complexes.
• Demonstration of the isomers acting as multi-dentate ligands with Cu(II), Ag(I), and Pb(II).
• Observation of rare solid-state isomerization and solvent cleavage reactions, with crystal packing influencing the process.

Conclusions:

• The [B20H18]2- dianion isomers exhibit versatile coordination chemistry.
• Solid-state isomerization of macropolyhedral boranes is less frequent than in solution.
• Crystal packing analysis provides criteria for predicting isomerization in crystalline boranes.