An Alkali Metal-Capped Cerium(IV) Imido Complex

Area of Science:

• Organometallic Chemistry
• Lanthanide Chemistry
• Inorganic Synthesis

Background:

• Terminal lanthanide-ligand multiple bonds are exceptionally rare due to expected high reactivity and poor orbital overlap.
• Previous strategies struggled to isolate these species due to charge polarization and instability.

Purpose of the Study:

• To develop a new strategy for isolating stable terminal lanthanide-ligand multiple bonds.
• To synthesize and characterize a terminal cerium-nitrogen multiple bond complex.

Main Methods:

• Utilized a tailored tris(hydroxylaminato) ligand framework, TriNOx(3-), for steric and electronic protection.
• Employed cerium(IV) complexes in the synthesis.
• Characterized the resulting complex using X-ray crystallography.

Main Results:

• Successfully isolated the first formal terminal cerium-nitrogen (Ce═N) multiple bond.
• The synthesized complex, [K(DME)2][Ce═N(3,5-(CF3)2C6H3)(TriNOx)], exhibits the shortest known Ce═N bond length at 2.119(3) Å.
• The TriNOx(3-) ligand framework prevented ligand scrambling, oligomerization, and reduction.

Conclusions:

• The developed strategy using cerium(IV) and the TriNOx(3-) ligand is effective for isolating terminal lanthanide-ligand multiple bonds.
• This work expands the known chemistry of lanthanides, demonstrating the feasibility of stabilizing highly reactive multiple bonds.