[(CH₃ )Al(CH₂ )]₁₂ : Methylaluminomethylene (MAM-12)

Area of Science:

• Organometallic Chemistry
• Materials Science
• Inorganic Chemistry

Background:

• The enigmatic "poly(aluminium-methyl-methylene)" structure, first reported in 1968, has remained largely uncharacterized.
• Previous attempts to synthesize well-defined structures yielded amorphous materials or low-yield clusters.

Purpose of the Study:

• To unravel the molecular structure of poly(aluminium-methyl-methylene).
• To develop a stable and efficient methylene transfer reagent derived from this structure.

Main Methods:

• Transmetalation reaction using gallium methylene [Ga₈ (CH₂ )₁₂ ] and trimethylaluminium (AlMe₃).
• Synthesis and characterization of the crystalline dodeca-aluminium complex [(CH₃ )₁₂ Al₁₂ (μ₃ -CH₂ )₁₂ ] (MAM-12).
• Revisiting prior synthetic approaches using titanium-based catalysts.

Main Results:

• The crystalline dodeca-aluminium complex (MAM-12) was reproducibly synthesized via transmetalation.
• Amorphous solids with MAM-12-like properties were obtained using a titanium-based method.
• The synthesized MAM-12 demonstrated efficacy as a methylene transfer reagent for ketones.

Conclusions:

• The molecular structure of poly(aluminium-methyl-methylene) has been successfully elucidated as the dodeca-aluminium complex MAM-12.
• MAM-12 serves as a valuable and efficient methylene transfer reagent in organic synthesis.
• This work provides a pathway to well-defined aluminium-methyl-methylene compounds.