Structural and Spectroscopic Comparison of Soft‐Se vs. Hard‐O Donor Bonding in Trivalent Americium/Neodymium Molecules

Abstract

Covalency is often considered to be an influential factor in driving An3+ vs. Ln3+ selectivity invoked by soft donor ligands. This is intensely debated, particularly the extent to which An3+/Ln3+ covalency differences prevail and manifest as the f‐block is traversed, and the effects of periodic breaks beyond Pu. Herein, two Am complexes, [Am{N(E=PPh2)2}3] (1‐Am, E=Se; 2‐Am, E=O) are compared to isoradial [Nd{N(E=PPh2)2}3] (1‐Nd, 2‐Nd) complexes. Covalent contributions are assessed and compared to U/La and Pu/Ce analogues. Through ab initio calculations grounded in UV‐vis‐NIR spectroscopy and single‐crystal X‐ray structures, we observe differences in f orbital involvement between Am–Se and Nd–Se bonds, which are not present in O‐donor congeners.

Cyclopentadienyl coordination induces unexpected ionic Am−N bonding in an americium bipyridyl complex

“…Despite the good agreement between the experimental and theoretical results, it is important to highlight the role of the dynamic correlation in the correct determination of these energies. As already reported in other americium(III) and neodymium(III) systems, at higher energies an overestimation of the f – f transitions are observed 52 , 53 . The importance of dynamical correlation in our systems is reflected in the most intense transitions.…”

“…977 cm −1 (61 nm) can be ascribed to the characteristic J = 0 ( 7 F 0 ) → J = 6 ( 7 F 6 ) transition and is predicted with an overestimation of about 814 cm −1 (9 nm) and splitting of 977 cm −1 (6 nm). Similar procedures have shown errors in the same order magnitude 17 , 52 , 53 . Moving to higher energies, the most intense band located between ca.…”

Computational Investigation of the Bonding in [(η5–Cp′)3(η1–Cp′)M]1– (M = Pu, U, Ce)

“…This feature of shorter M –C bond metrics is even more extreme when the M –C25 bond is compared between the actinides 1-U , 1-Pu and the lanthanides 1-Ce , 1-Pr , where a difference of 0.065 Å is observed for the Pu/Ce pair when the 0.01 Å difference in the ion size is considered, which is well beyond the 0.002–0.003 Å error in the bond measurement data, as shown in Table and Figure . This type of trend has also been observed in other ligand environments, namely, the M­[N­(E = PR 2 ) 3 ] 3 (M = Am, Pu, U, Ln; E = Te, Se, S; R = i Pr, Ph) family of complexes. − …”

[AnI3(THF)4] (An = Np, Pu) Preparation Bypassing An0 Metal Precursors: Access to Np3+/Pu3+ Nonaqueous and Organometallic Complexes

“…Note that, in principle, AnO 2 (An = Np, Pu) could be dissolved in HI (aq) to directly produce An 3+ (aq) , similar to the previously mentioned synthesis of [PuBr 3 (DME) 2 ]. 55 Such a route is likely a viable approach for the transplutonium elements Cm−Cf due to the stability of their trivalent oxidation state, 7,8,107,108 and it has been demonstrated with the synthesis of [AmBr 3 (THF) 4 ] by the dissolution of AmO 2 . 107 However, the relative redox instability of Np 3+ , coupled with the desire to develop homologous routes to both Np 3+ and Pu 3+ starting materials, led us to the methods herein.…”