A comprehensive approach for elucidating the interplay between 4f and 4f 5d configurations in Ln complexes.

Lanthanides (Ln) are typically found in the +3 oxidation state. However, in recent decades, their chemistry has been expanded to include the less stable +2 oxidation state across the entire series except promethium (Pm), facilitated by the coordination of ligands such as trimethylsilylcyclopentadienyl, CHSiMe (Cp'). The complexes have been the workhorse for the synthesis and theoretical study of the fundamental aspects of divalent lanthanide chemistry, where experimental and computational evidence have suggested the existence of different ground state (GS) configurations, 4f or 4f 5d, depending on the specific metal.

Correction: Impact of lanthanide ion complexation and temperature on the chemical reactivity of ,,','-tetraoctyl diglycolamide (TODGA) with the dodecane radical cation.

Correction for 'Impact of lanthanide ion complexation and temperature on the chemical reactivity of ,,','-tetraoctyl diglycolamide (TODGA) with the dodecane radical cation' by Gregory P. Horne , , 2023, , 16404-16413, https://doi.org/10.

Effect of -element complexation on the radiolysis of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]).

A systematic study of the impact on the chemical reactivity of the oxidising -dodecane radical cation (RH˙) with -element complexed 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) has been undertaken utilizing time-resolved electron pulse radiolysis/transient absorption spectroscopy and high-level quantum mechanical calculations. Lanthanide ion complexed species, [Ln((HEH[EHP]))], exhibited vastly increased reactivity (over 10× faster) in comparison to the non-complexed ligand in -dodecane solvent, whose rate coefficient was = (4.66 ± 0.

Co-Crystallization of Plutonium(III) and Plutonium(IV) Diglycolamides with Pu(III) and Pu(IV) Hexanitrato Anions: A Route to Redox Variants of [Pu(DGA)][Pu(NO)].

-tetramethyl diglycolamide (TMDGA), a methylated variant of the diglycolamide extractants being proposed as curium holdback reagents in advanced used nuclear fuel reprocessing technologies, has been crystallized with plutonium, a transuranic actinide that has multiple accessible oxidation states. Two plutonium TMDGA complexes, [Pu(TMDGA)][Pu(NO)] and[Pu(TMDGA)][Pu(NO)]·0.75MeOH, were crystallized through solvent diffusion of a reaction mixture containing plutonium(III) nitrate and TMDGA.

Altering the spectroscopy, electronic structure, and bonding of organometallic curium(III) upon coordination of 4,4'-bipyridine.

Structural and electronic characterization of (Cp'Cm)(μ-4,4'-bpy) (Cp' = trimethylsilylcyclopentadienyl, 4,4'-bpy = 4,4'-bipyridine) is reported and provides a rare example of curium-carbon bonding. Cp'Cm displays unexpectedly low energy emission that is quenched upon coordination by 4,4'-bipyridine. Electronic structure calculations on Cp'Cm and (Cp'Cm)(μ-4,4'-bpy) rule out significant differences in the emissive state, rendering 4,4'-bipyridine as the primary quenching agent.

Impact of lanthanide ion complexation and temperature on the chemical reactivity of ,,','-tetraoctyl diglycolamide (TODGA) with the dodecane radical cation.

The impact of trivalent lanthanide ion complexation and temperature on the chemical reactivity of ,,','-tetraoctyl diglycolamide (TODGA) with the -dodecane radical cation (RH˙) has been measured by electron pulse radiolysis and evaluated by quantum mechanical calculations. Additionally, Arrhenius parameters were determined for the reaction of the non-complexed TODGA ligand with the RH˙ from 10-40 °C, giving the activation energy ( = 17.43 ± 1.

Radium Revisited: Revitalization of the Coordination Chemistry of Nature's Largest +2 Cation.

The crystallization, single crystal structure, and Raman spectroscopy of Ra(NO) have been investigated by experimentation and theory, which represent the first pure radium compound characterized by single crystal X-ray diffraction. The Ra centers are bound by six chelating nitrate anions to form an anticuboctahedral geometry. The Raman spectrum acquired from a single crystal of Ra(NO) generally occurs at a lower frequency than found in Ba(NO), as expected.

Synthesis and Crystallographic Characterization of a Reduced Bimetallic Yttrium -Metallocene Hydride Complex, [K(crypt)][(μ-Cp)Y(μ-H)] (Cp = MeSi[CH(SiMe)-3]), with a 3.4 Å Yttrium-Yttrium Distance.

The reduction of a bimetallic yttrium -metallocene hydride was examined to explore the possible formation of Y-Y bonds with 4d Y(II) ions. The precursor [CpY(μ-H)(THF)] (Cp = MeSi[CH(SiMe)-3]) was synthesized by hydrogenolysis of the allyl complex CpY(η-CH)(THF), which was prepared from (CH)MgCl and [CpY(μ-Cl)]. Treatment of [CpY(μ-H)(THF)] with excess KC in the presence of one equivalent of 2.

Isolation of a californium(II) crown-ether complex.

The actinides, from californium to nobelium (Z = 98-102), are known to have an accessible +2 oxidation state. Understanding the origin of this chemical behaviour requires characterizing Cf materials, but investigations are hampered by the fact that they have remained difficult to isolate. This partly arises from the intrinsic challenges of manipulating this unstable element, as well as a lack of suitable reductants that do not reduce Cf to Cf°.

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

Variations in bonding between trivalent lanthanides and actinides is critical for reprocessing spent nuclear fuel. The ability to tune bonding and the coordination environment in these trivalent systems is a key factor in identifying a solution for separating lanthanides and actinides. Coordination of 4,4'-bipyridine (4,4'-bpy) and trimethylsilylcyclopentadienide (Cp') to americium introduces unexpectedly ionic Am-N bonding character and unique spectroscopic properties.

Creation of an unexpected plane of enhanced covalency in cerium(III) and berkelium(III) terpyridyl complexes.

Controlling the properties of heavy element complexes, such as those containing berkelium, is challenging because relativistic effects, spin-orbit and ligand-field splitting, and complex metal-ligand bonding, all dictate the final electronic states of the molecules. While the first two of these are currently beyond experimental control, covalent M‒L interactions could theoretically be boosted through the employment of chelators with large polarizabilities that substantially shift the electron density in the molecules. This theory is tested by ligating Bk with 4'-(4-nitrophenyl)-2,2':6',2"-terpyridine (terpy*), a ligand with a large dipole.

Influence of uranyl complexation on the reaction kinetics of the dodecane radical cation with used nuclear fuel extraction ligands (TBP, DEHBA, and DEHiBA).

Specialized extractant ligands - such as tri-butyl phosphate (TBP), ,-di-(2-ethylhexyl)butyramide (DEHBA), and ,-di-2-ethylhexylisobutryamide (DEHiBA) - have been developed for the recovery of uranium from used nuclear fuel by reprocessing solvent extraction technologies. These ligands must function in the presence of an intense multi-component radiation field, and thus it is critical that their radiolytic behaviour be thoroughly evaluated. This is especially true for their metal complexes, where there is negligible information on the influence of complexation on radiolytic reactivity, despite the prevalence of metal complexes in used nuclear fuel reprocessing solvent systems.

Synthesis, characterization, and theoretical analysis of a plutonyl phosphine oxide complex.

The interplay of bond strength and covalency are examined in AnOCl(OPcy) (An = Pu, U) complexes. The synthesis of -PuOCl(OPcy), 1-Pu, has been carried out and confirmed by single crystal X-ray diffraction along with UV-vis-NIR, and P NMR spectroscopies. Theoretical analysis finds that despite a higher calculated covalency for the Pu-Cl interaction, the Pu-OPcy interaction is stronger due to the accumulation of electron density in the interatomic region.

Influence of Outer-Sphere Anions on the Photoluminescence from Samarium(II) Crown Complexes.

Three samarium(II) crown ether complexes, [Sm(15-crown-5)]I (), [Sm(15-crown-5)]I·CHCN (), and [Sm(benzo-15-crown-5)]I (), have been prepared via the reaction of SmI with the corresponding crown ether in either THF or acetonitrile in good to moderate yields. The compounds have been characterized by single crystal X-ray diffraction and a variety of spectroscopic techniques. In all cases, the Sm(II) centers are sandwiched between two crown ether molecules and are bound by the five etheric oxygen atoms from each crown ether to yield 10-coordinate environments.

Understanding the Stabilization and Tunability of Divalent Europium 2.2.2B Cryptates.

Lanthanides such as europium with more accessible divalent states are useful for studying redox stability afforded by macrocyclic organic ligands. Substituted cryptands, such as 2.2.

Origin of Bond Elongation in a Uranium(IV) -Bis(imido) Complex.

The activation of U-N multiple bonds in an imido analogue of the uranyl ion is accomplished by using a system that is very electron-rich with sterically encumbering ligands. Treating the uranium(VI) -bis(imido) UI(NDIPP)(THF) (DIPP = 2,6-diisopropylphenyl and THF = tetrahydrofuran) with -butyl(dimethylsilyl)amide (NTSA) results in a reduction and rearrangement to form the uranium(IV) -bis(imido) [U(NDIPP)(NTSA)]K (). Compound features long U-N bonds, pointing toward substantial activation of the N═U═N unit, as determined by X-ray crystallography and H NMR, IR, and electronic absorption spectroscopies.

Exploring the Oxidation States of Neptunium with Schiff Base Coordination Complexes.

A pair of neptunium Schiff base coordination complexes, and { = ,'-bis[(4,4'-diethylamino)salicylidene]-1,2-phenylenediamine}, have been synthesized and analyzed by several characterization methods including single-crystal X-ray diffraction, electronic absorption, H NMR, cyclic voltammetry, and theoretical interpretation. Structural analysis reveals that and are isomorphous with the previously reported and (M = Pu, Ce, U, Th) complexes, respectively, allowing for a direct comparison across the series. The reduction of or direct synthesis from a (NpO) source shows evidence of a pentavalent neptunyl species as determined by UV/vis/NIR and H NMR spectroscopy.

Structure and Characterization of an Americium Bis(-diethyl)dithiophosphate Complex.

A facile synthesis of an americium complex with a sulfur-donor ligand has been developed, allowing characterization of americium bonding from multiple perspectives via several techniques. Reaction of Am with SP(OEt) yields the tetrakis complex [Am(SP(OEt))] that can be crystallized as the tetraphenylarsonium salt. Structures obtained from single crystal X-ray diffraction show bond length discrepancies from the neodymium analogue consistent with the soft-donor bond enhancement common to actinides.

Compression of curium pyrrolidine-dithiocarbamate enhances covalency.

Curium is unique in the actinide series because its half-filled 5f  shell has lower energy than other 5f  configurations, rendering it both redox-inactive and resistant to forming chemical bonds that engage the 5f shell. This is even more pronounced in gadolinium, curium's lanthanide analogue, owing to the contraction of the 4f orbitals with respect to the 5f orbitals. However, at high pressures metallic curium undergoes a transition from localized to itinerant 5f electrons.

Trivalent f-Element Squarates, Squarate-Oxalates, and Cationic Materials, and the Determination of the Nine-Coordinate Ionic Radius of Cf(III).

The synthesis, structure, and solid-state UV-vis-NIR spectroscopy of four new f-element squarates, M(CO)(HO) (M = Eu, Am, Cf) and Sm(CO)(COOH)(HO)·0.5HO, four new cationic lanthanide squarate chlorides, [M(CO)(HO)]Cl·5HO (M = Eu, Dy, Ho Er), and two new actinide squarate oxalates, M(CO)(CO)(HO) (M = Am, Cf), are presented. All of the metal centers are trivalent.

Evidence of Alpha Radiolysis in the Formation of a Californium Nitrate Complex.

Well-characterized complexes of transplutonium elements are scarce because of the experimental challenges of working with these elements and the rarity of the isotopes. This leads to a lack of structural and spectroscopic data needed to understand the nature of chemical bonds in these compounds. In this work, the synthesis of Cf(DOPO ) (NO )(py) (DOPO =2,4,6,8-tetra-tert-butyl-1-oxo-1H-phenoxazin-9-olate; py=pyridine) is reported, in which the nitrate anion is hypothesized to form through the α-radiolysis-induced reaction of pyridine and/or the ligand.

Probing a variation of the inverse-trans-influence in americium and lanthanide tribromide tris(tricyclohexylphosphine oxide) complexes.

The synthesis, characterization, and theoretical analysis of meridional americium tribromide tris(tricyclohexylphosphine oxide), , has been achieved and is compared with its early lanthanide (La to Nd) analogs. The data show that homo ligands display significantly shorter bonds than the or hetero ligands. This is particularly pronounced in the americium compound.

Structure, Spectroscopy, and Theoretical Analysis of Zero- and Three-Dimensional Lithium Plutonium Fluorides: LiPuF and LiPuF.

The reaction of PuO with HF and LiF under hydrothermal conditions results in the formation of LiPuF and LiPuF. These compounds were structurally characterized using single-crystal X-ray diffraction, and UV-vis-near-IR absorption spectroscopy was employed to confirm the oxidation state of the plutonium in the compounds as 4+. The structure of LiPuF consists of [PuF] anions that adopt a bicapped trigonal-prismatic geometry with approximate symmetry.