Synthesis, Characterization, and Reactivity Studies of New Cyclam-Based Y(III) Complexes

Area of Science:

• Organometallic Chemistry
• Catalysis
• Synthetic Chemistry

Background:

• Cyclam macrocycles are versatile ligands in coordination chemistry.
• Yttrium complexes offer unique reactivity for catalytic applications.
• Understanding ligand protonation is crucial for controlling reactivity.

Purpose of the Study:

• To synthesize and characterize new yttrium-cyclam complexes.
• To investigate the protonation behavior of yttrium-cyclam complexes.
• To evaluate the catalytic activity of these complexes in hydroamination.

Main Methods:

• Synthesis of yttrium complexes using H2Bn2Cyclam and substituted derivatives.
• Protonation studies using [HNMe3][BPh4] and DFT analysis.
• Characterization via NMR spectroscopy and preliminary catalytic assays.

Main Results:

• Successful synthesis of [(Bn2Cyclam)Y(N(SiMe3)2)] and related complexes.
• Observation of macrocycle protonation following orbital control (DFT).
• Formation of organometallic yttrium-THF-chloro-lithium intermediates.
• Identification of [(3,5-tBu2Bn2Cyclam)Y(CH2SiMe3)] via variable temperature NMR.
• Demonstration of high catalytic efficiency for intramolecular hydroamination.

Conclusions:

• Novel yttrium-cyclam complexes were synthesized and characterized.
• Protonation of the cyclam ligand is influenced by electronic factors.
• The yttrium complex [Y{(η3-3,5-tBu2Bn)2Cyclam}Li(THF)] is a potent catalyst for intramolecular hydroamination.