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. 2021 Oct 4;12(43):14383-14388.
doi: 10.1039/d1sc04666g. eCollection 2021 Nov 10.

Synthesis and electronic structure analysis of the actinide allenylidenes, [{(NR2)3}An(CCCPh2)]- (An = U, Th; R = SiMe3)

Greggory T Kent  1 , Xiaojuan Yu  2 , Guang Wu  1 , Jochen Autschbach  2 , Trevor W Hayton  1
Affiliations

Synthesis and electronic structure analysis of the actinide allenylidenes, [{(NR2)3}An(CCCPh2)]- (An = U, Th; R = SiMe3)

Greggory T Kent et al. Chem Sci. .

Abstract

The reaction of [AnCl(NR2)3] (An = U, Th, R = SiMe3) with in situ generated lithium-3,3-diphenylcyclopropene results in the formation of [{(NR2)3}An(CH[double bond, length as m-dash]C[double bond, length as m-dash]CPh2)] (An = U, 1; Th, 2) in good yields after work-up. Deprotonation of 1 or 2 with LDA/2.2.2-cryptand results in formation of the anionic allenylidenes, [Li(2.2.2-cryptand)][{(NR2)3}An(CCCPh2)] (An = U, 3; Th, 4). The calculated 13C NMR chemical shifts of the Cα, Cβ, and Cγ nuclei in 2 and 4 nicely reproduce the experimentally assigned order, and exhibit a characteristic spin-orbit induced downfield shift at Cα due to involvement of the 5f orbitals in the Th-C bonds. Additionally, the bonding analyses for 3 and 4 show a delocalized multi-center character of the ligand π orbitals involving the actinide. While a single-triple-single-bond resonance structure (e.g., An-C[triple bond, length as m-dash]C-CPh2) predominates, the An[double bond, length as m-dash]C[double bond, length as m-dash]C[double bond, length as m-dash]CPh2 resonance form contributes, as well, more so for 3 than for 4.

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Conflict of interest statement

There are no conflicts to declare.

Figures

Scheme 1
Scheme 1. Synthesis of complexes 1–4.
Fig. 1
Fig. 1. Solid-state structure of 1 shown with 50% probability ellipsoids. Hydrogen atoms omitted for clarity.
Fig. 2
Fig. 2. Solid-state structure of [Li(2.2.2-cryptand)][{(NR2)3}U(CCCPh2)] (3) shown with 50% probability ellipsoids. Hydrogen atoms, [Li(2.2.2-cryptand)], and pentane solvate omitted for clarity.
Fig. 3
Fig. 3. Isosurfaces (±0.03 a.u.) of selected NLMOs for 3 and 4. The α spin NLMOs of 3 are shown, weight-% metal character and 6d vs. 5f contributions at U are averaged over spins.
See this image and copyright information in PMC

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