Mapping the Pathway to Organocopper(II) Complexes Relevant to Atom Transfer Radical Polymerization.

Area of Science:

• Organometallic Chemistry
• Polymerization Catalysis
• Spectroscopy

Background:

• Copper complexes are crucial in atom transfer radical polymerization (ATRP).
• Understanding byproducts in ATRP is essential for catalyst and process optimization.
• Organocopper complexes can form as reactive intermediates or byproducts.

Purpose of the Study:

• To synthesize and characterize the rare organocopper(II) complex [Cu(Me6tren)(CH2CN)]+.
• To elucidate the formation mechanism of this complex as a potential ATRP byproduct.
• To investigate the role of intermediates in the reaction pathway.

Main Methods:

• Controlled potential electrolysis for complex synthesis.
• Time-resolved UV-vis spectroscopy to monitor reaction kinetics.
• Electron paramagnetic resonance (EPR) spectroscopy (continuous wave, pulse, HYSCORE, ENDOR) for structural and electronic characterization.
• Density functional theory (DFT) calculations for computational support.

Main Results:

• The organocopper(II) complex [Cu(Me6tren)(CH2CN)]+ was successfully generated.
• [Cu(Me6tren)Br]+ was identified as a key intermediate.
• Spectroscopic data confirmed a C-bound cyanomethylate ligand, distinct from N-bound isomers.
• DFT calculations supported the experimental findings regarding complex geometries and spectroscopic signatures.

Conclusions:

• A detailed mechanism for the formation of the unusual organocopper(II) complex has been established.
• The study provides insights into potential byproduct formation in copper-catalyzed ATRP.
• Advanced spectroscopic techniques combined with computational methods are powerful tools for characterizing transient organometallic species.