Cyclooctatetraenyl calcium and strontium amido complexes

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Heavy alkaline-earth metals (calcium and strontium) exhibit unique coordination chemistry.
• Cyclooctatetraenyl (C8H8) is a versatile ligand in organometallic chemistry.
• Bis(trimethylsilyl)amido ligands offer steric bulk and electronic stabilization.

Purpose of the Study:

• To synthesize and characterize novel cyclooctatetraenyl complexes of calcium and strontium.
• To explore the reactivity and structural diversity of these complexes.
• To establish a foundational synthetic approach for cyclooctatetraenyl heavy alkaline-earth metal amido complexes.

Main Methods:

• Synthesis of inverse sandwich and mixed-metal complexes using alkali metal amides and cyclooctatetraenyl precursors.
• Characterization of synthesized compounds using X-ray diffraction.
• Investigation of reaction pathways including stepwise synthesis and redistribution reactions.

Main Results:

• Successful synthesis of inverse sandwich amido complexes of calcium and strontium, [[{(Me3Si)2N}M(thf)x]2(μ-C8H8)] (M = Ca, Sr).
• Formation of a mixed potassium calcium complex, [[{(Me3Si)2N}Ca(thf)](μ-C8H8)K].
• Characterization of several discrete and polymeric structures, with identification of Ca-Cπ interactions in some cases.

Conclusions:

• This work presents the first synthetic approach to cyclooctatetraenyl heavy alkaline-earth metal amido complexes.
• The study highlights the lability of coordinated thf ligands and facile redistribution reactions as key challenges.
• The synthesized complexes provide a basis for further exploration of heavy alkaline-earth metal organometallic chemistry.