Reversible binding and reduction of dinitrogen by a uranium(III) pentalene complex

Area of Science:

• Organometallic Chemistry
• Uranium Chemistry
• Coordination Chemistry

Background:

• Mixed-sandwich compounds offer unique electronic and steric properties.
• Uranium(III) complexes are of interest for their reactivity and potential applications.

Purpose of the Study:

• To synthesize and characterize a novel Uranium(III) mixed-sandwich compound.
• To investigate the reactivity of this compound with small molecules like dinitrogen.

Main Methods:

• Sequential reaction of uranium triiodide (UI(3)) with potassium cyclopentadienyl (KCp) and a potassium-based cyclooctatetraene derivative.
• Crystallographic characterization of the synthesized compound.
• Reversible reaction with dinitrogen (N(2)).

Main Results:

• Successful synthesis and crystallographic characterization of the Uranium(III) mixed-sandwich compound [U(eta-Cp)(eta-C(8)H(4)[Si(i)Pr(3)-1,4](2))] (1).
• Reversible reaction of compound 1 with dinitrogen to form a dimeric complex [[U(eta-Cp)(eta-C(8)H(4)[Si(i)Pr(3)-1,4](2))](2)(mu-eta(2):eta(2)-N(2))] (2).
• X-ray crystal structure of complex 2 revealed a sideways-bound, bridging diazenido (N(2)(2-)) ligand.

Conclusions:

• The Uranium(III) mixed-sandwich complex 1 is a stable, characterizable compound.
• The reversible binding of dinitrogen to form a bridging diazenido ligand is a significant finding in uranium coordination chemistry.