Scandium─Group 13 Heterobimetallic Methylidene Clusters.

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Scandium complexes with tetramethylmetalate ligands (Cp*₂Sc(EMe₄)) were synthesized.
• These complexes serve as precursors for novel cluster compounds.
• Understanding the reactivity of scandium organometallics is crucial for developing new synthetic methodologies.

Purpose of the Study:

• To synthesize and characterize new scandium tetramethylgallate and tetramethylindate complexes.
• To investigate the reactivity of these complexes in the formation of methylidene clusters.
• To compare the reactivity of scandium complexes with related yttrium and lutetium complexes.

Main Methods:

• Synthesis of Cp*₂Sc(AlMe₄) from Cp*₂ScCl(thf) and LiAlMe₄/AlMe₃.
• Donor-assisted trimethyltriel exchange to yield Cp*₂Sc(EMe₄) (E = Ga, In).
• Thermal treatment in benzene and reactions with excess metal alkyls.
• Characterization using SC-XRD, ICP-OES, elemental analysis, and NMR spectroscopy (¹H, ¹³C{¹H}, ⁴⁵Sc).

Main Results:

• Successful synthesis of the first scandium tetramethylgallate and tetramethylindate complexes.
• Formation of methylidene clusters Cp*₆Sc₄E₈(CH₂)₁₂Me₆ (E = Ga, In) via methyl group deprotonation.
• Observation of different reactivity pathways compared to yttrium analogs, leading to Ga₈(CH₂)₁₂ or Cp*₄Sc₄In₈(CH₂)₁₂Me₈ clusters.
• Isolation of Me₂InCp*InMe₃ from reactions involving InMe₃ and HCp*.

Conclusions:

• Scandium complexes exhibit unique reactivity in forming methylidene clusters, distinct from lighter lanthanides.
• The study expands the known family of organometallic clusters with novel scandium-containing structures.
• These findings contribute to the fundamental understanding of metal-ligand interactions and cluster assembly.