Well-Defined Scandacyclopropenes: Synthesis, Structure, and Reactivity.

Area of Science:

• Organometallic Chemistry
• Rare-Earth Chemistry
• Synthetic Chemistry

Background:

• Transition metallacyclopropenes are well-studied, but rare-earth analogues remained elusive.
• Metallacyclopropenes are key intermediates in various catalytic cycles.

Purpose of the Study:

• To synthesize and characterize the first well-defined rare-earth metallacyclopropenes.
• To investigate the structural, electronic, and reactive properties of these novel compounds.

Main Methods:

• Synthesis of scandacyclopropenes.
• Structural characterization using X-ray diffraction and spectroscopy.
• Density Functional Theory (DFT) calculations.
• Reactivity studies with various small molecules.

Main Results:

• Successfully synthesized three isolable scandacyclopropenes.
• Characterization revealed a delocalized three-center two-electron (3c-2e) aromatic system.
• Scandacyclopropenes exhibited diverse reactions including insertion, metathesis, and redox processes with small molecules like phenylacetylene, TMSN3, phenazine, TMSNCO, N2O, PhSSPh, and PhNNPh.

Conclusions:

• Scandacyclopropenes represent the first class of well-defined rare-earth metallacyclopropenes.
• The unique electronic structure and strained ring system impart diversified and novel reactivity.
• These findings expand the scope of metallacyclopropene chemistry and offer new possibilities for rare-earth metal applications.