Carbene Complexes of Neptunium

Area of Science:

• Organometallic Chemistry
• Actinide Chemistry
• Inorganic Chemistry

Background:

• Organotransuranium chemistry has historically been limited to π-bonded carbocyclic and σ-bonded hydrocarbyl derivatives.
• Structurally verified transuranium-carbon multiple or dative bonds have not been previously reported.

Purpose of the Study:

• To synthesize and characterize novel transuranium-carbene derivatives of neptunium(III).
• To investigate the nature of transuranium-carbon bond interactions, specifically multiple and dative bonds.
• To explore the reactivity of these new complexes and their implications for actinide chemistry.

Main Methods:

• Synthesis of neptunium(III) complexes using diphosphoniomethanide precursors.
• Characterization of synthesized complexes, including N-heterocyclic carbene-neptunium(III) derivatives.
• Utilized cerium synthetic surrogates for a scaled-down, pre-choreographed approach.
• Employed computational analysis to understand bonding and compare with other elements.

Main Results:

• Successfully synthesized and characterized diphosphonio-alkylidene- and N-heterocyclic carbene-neptunium(III) complexes.
• These complexes exhibit polarized-covalent σ²π² multiple and dative σ² single transuranium-carbon bond interactions.
• The Np(III)═C bonds show significant covalency, comparable to U(IV)═C bonds.
• Preliminary reactivity studies introduced multiple bond metathesis to transuranium chemistry.

Conclusions:

• This work reports the first structurally verified transuranium-carbon multiple and dative bonds.
• The synthesis of these neptunium(III) complexes provides a platform for comparing 5f-element bonding and reactivity.
• The findings extend the known scope of metallo-Wittig reactions to actinide oxidation states III-VI.