Synthesis and comparison of iso-structural f-block metal complexes (Ce, U, Np, Pu) featuring η6-arene interactions

Jesse Murillo; Conrad A P Goodwin; Lauren Stevens; Skye Fortier; Andrew J Gaunt; Brian L Scott

doi:10.1039/d3sc02194g

Synthesis and comparison of iso-structural f-block metal complexes (Ce, U, Np, Pu) featuring η⁶-arene interactions

Chem Sci. 2023 Jun 20;14(27):7438-7446. doi: 10.1039/d3sc02194g. eCollection 2023 Jul 12.

Authors

Jesse Murillo^{1

2}, Conrad A P Goodwin², Lauren Stevens^{2

3}, Skye Fortier¹, Andrew J Gaunt², Brian L Scott³

Affiliations

¹ Department of Chemistry and Biochemistry, University of Texas at El Paso El Paso Texas 79968 USA asfortier@utep.edu.
² Chemistry Division, Los Alamos National Laboratory Los Alamos New Mexico 87545 USA gaunt@lanl.gov.
³ Materials Physics and Applications Division, Los Alamos National Laboratory Los Alamos New Mexico 87545 USA.

Abstract

Reaction of the terphenyl bis(anilide) ligand [{K(DME)₂}₂L^Ar] (L^Ar = {C₆H₄[(2,6-ⁱPr²C₆H₃)NC₆H₄]₂}^2-) with trivalent chloride "MCl₃" salts (M = Ce, U, Np) yields two distinct products; neutral L^ArM(Cl)(THF) (1^M) (M = Np, Ce), and the "-ate" complexes [K(DME)₂][(L^Ar)Np(Cl)₂] (2^Np) or ([L^ArM(Cl)₂(μ-K(X)₂)])_∞ (2^Ce, 2^U) (M = Ce, U) (X = DME or Et₂O) (2^M). Alternatively, analogous reactions with the iodide [MI₃(THF)₄] salts provide access to the neutral compounds L^ArM(I)(THF) (3^M) (M = Ce, U, Np, Pu). All complexes exhibit close arene contacts suggestive of η⁶-interactions with the central arene ring of the terphenyl backbone, with 3^M comprising the first structurally characterized Pu η⁶-arene moiety. Notably, the metal-arene bond metrics diverge from the predicted trends of metal-carbon interactions based on ionic radii, with the uranium complexes exhibiting the shortest M-C_centroid distance in all cases. Overall, the data presents a systematic study of f-element M-η⁶-arene complexes across the early actinides U, Np, Pu, and comparison to cerium congeners.