A permanently porous organic framework assembled and stabilized solely by non-covalent chalcogen bonding is reported. Empirical and computational studies reveal the characteristic influence of the ope...

Experimental and computational analyses of [M(pdtz)3(H2O)3]·3.5H2O (M3+ = Pu3+–Cm3+, La3+–Nd3+, and Sm3+–Ho3+, pdtz– = 5-(2-pyridyl)-1H-tetrazolate) were conducted to understand potential differences ...

Although the trivalent actinides are similar to the lanthanide series in terms of chemistry and bonding, their structures and properties can diverge significantly. Here, the authors report a series of...

Complexes containing hydroxide, water and dinitrogen ligands detected as researchers probe chemistry on the edge of the actinide series

This review outlines the structure and chemistry of divalent lanthanides and actinides in small molecule systems, focusing on the less accessible diva…

This theoretical study investigates the UV–vis absorption properties of U4+-containing aqueous solutions and their relationship with the nature of aqua-complexes present at varying acidic levels. High...

An example of a 249Bk3+ phosphine oxide complex has been prepared to examine and quantify the effects of the inverse trans-influence (ITI) on a late actinide complex. This has been accomplished through a comparison of cis and trans Bk-ligand bonds in the meridional berkelium(III) complex, BkBr3(OPCy3)3 (OPCy3 = tricyclohexylphosphine oxide). A detailed bond metric analysis was completed that includes the shortest published distance for a Bk3+–O bond, attributed to the smaller coordination number of Bk3+ of six in mer-BkBr3(OPCy3)3. ITI calculations of the trans Bk3+–O bond provide an ITI value (98.5(2)%) comparable to that of mer-AmBr3(OPCy3)3 (98.2(2)%) and indicate a small 5f orbital contribution to bonding. This effect is discussed in the context of the isomorphous lanthanide(III) series where the ITI is calculated to be higher for mer-BkBr3(OPCy3)3 than in most Ln3+ analogues.

A trivalent plutonium–pyrazinyl–tetrazolate complex Na2[Pu(Hdtp)(dtp)2(H2O)4]·9H2O (Pu_dtp, H2dtp = 2,3-di-1H-tetrazol-5-ylpyrazine) was synthesized through metathesis reaction of plutonium bromide an...

Nature Chemistry - The most common oxidation state for lanthanide elements is +3, and, beyond cerium, examples of these elements exhibiting higher oxidation states remain scarce. Now, a molecular...

Synthesis could help chemists better understand bonding

Diethylenetriaminepentaacetic acid (DTPA) is a frequently used chelator in the nuclear and medical industries, especially for the complexation of trivalent actinides. However, structural data on these complexes in the solid-state have long remained elusive. Herein, a detailed structural analysis of the presented crystal structures of [C(NH2)3]4[Nd(DTPA)]2·nH2O and [C(NH2)3]4[Am(DTPA)]2·nH2O, where [C(NH2)3]+ is guanidinium, details the subtle differences in the Lewis acidity between a lanthanide/actinide pair of similar ionic sizes. Contractions in nitrogen–metal bond lengths between neodymium(III) and americium(III) were observed, while the metal–oxygen bonds remained relatively consistent, highlighting the marginal favorability for actinide complexation over the lanthanides with moderately soft N-donors. Spectroscopic analysis shows significant splitting of many transitions and relatively strong electronic interactions with traditionally low-intensity transitions in the americium complex, as is demonstrated in the 7F0→7F5 transitions. Pressure-induced spectroscopic analysis showed surprisingly little effect on the americium complex, with 5f→5f transitions either not shifting or marginally shifting from 2 to 3 nm at 11.93 ± 0.06 GPa─atypical of a soft, N-donor americium complex under pressure. Large voids occupied by water molecules in between the complexes within the crystal structure may be responsible for the lack of pressure response in the 5f→5f transitions.

The isotope is critical for understanding Earth’s origins. An accurate half-life is key—and researchers may have finally measured it

An octa-hydrated curium compound [Cm(H2O)8](Hdtp)(dtp)·H2O (Cm1, H2dtp = 2,3-di(tetrazol-5-yl)pyrazine) along with its lanthanide analogues [Ln(H2O)8](Hdtp)(dtp)·H2O (Ln1, Ln3+ = La3+–Nd3+, Sm3+–Lu3+)...

Experimental observations of the half life of rutherfordium-252 demonstrate that its stability lies well within the limits required for full atoms to form

Three Sm(II) dibenzo-24-crown-8 (db24c8) complexes were synthesized in anhydrous, air-free conditions via the reaction of SmI2 with db24c8 and tetrabutylammonium tetraphenylborate ([TBA][BPh4]; where ...

Polyamine-supported CoII complexes catalyzed the oxidative fluorination of saturated hydrocarbons, in some instances selectively, when combined with Selectfluor and CsF, producing fluorinated product...

The cis-anti-cis and cis-syn-cis isomers of [Sm(dicyclohexano-18-crown-6)(H2O)2]I2 exhibiting trans water molecules bound to the Sm2+ ion have been isolated and characterized. Sm2+ possesses an electrochemical potential sufficient for water reduction, and thus these complexes add to the recent body of evidence that the oxidation of Sm2+ by water can operate by a mechanism that is not straightforward. These complexes are obtained by the direct addition of stoichiometric amounts of water to solutions of the respective Sm(dicyclohexano-18-crown-6)I2 isomers under an inert atmosphere. The parent complex, Sm(dicyclohexano-18-crown-6)I2, lacking coordinating water molecules can be obtained through rigorous exclusion of water. It was determined that the bulky cyclohexano-substituents deter intramolecular interactions between [Sm(dicyclohexano-18-crown-6)(H2O)2]I2 complexes and slow the oxidization of the metal centers. The extent of the stability of these complexes to the presence of water has been further probed through cyclic voltammetry, where it was found that the redox potential of both isomers of [Sm(dicyclohexano-18-crown-6)(H2O)2]I2 maintains quasi-reversible behavior with a 50,000-fold excess of water to Sm2+ in solution with the cis-syn-cis complex being quasi-reversible at even higher concentrations of water. Solution-phase spectroscopy of these complexes in acetonitrile shows a corresponding hypsochromic shift of the Sm2+ 4f → 5d transition typically observed in the visible region from Sm2+ complexes. The crystalline compounds obtained in this study support solid-state spectroscopic trends observed from other Sm2+ crown-ether complexes containing iodide counterions, wherein the proximity of the iodide ions to the metal center determines whether the complex can exhibit 4f → 4f photoluminescence.

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 exc...

Previous work at the MagLab demonstrated that it is possible to design molecules containing a LuII ion such that its lone unpaired electron is shielded against harmful magnetic noise, giving rise to a...

High-valent nickel species are implicated as intermediates in industrially relevant chemical transformations and in the catalytic cycles of metalloenzymes. Although a small number of tetravalent NiX4 ...

To develop the structural chemistry of radium, the halide compounds RaX2·H2O and RaX2·2H2O (X– = Cl– and Br–) have been synthesized and characterized and serve as benchmarks for comparisons with more complex compounds in the future. In contrast with historic reports on the structural chemistry of radium, the Ra2+ chlorides differ from their Ba2+ analogues. For MCl2·H2O (M2+ = Ba2+, Ra2+), the variance between the metal coordination environments manifests as a small, local distortion that becomes more apparent in the extended structure. However, differences between RaCl2·2H2O and BaCl2·2H2O are more pronounced with a 10-coordinate Ra2+ cation being observed instead of a nine-coordinate Ba2+ in BaCl2·2H2O. RaBr2·nH2O (n = 1 or 2) are isomorphous with the Ba2+ analogues. Raman spectroscopy was used as an additional probe of these compounds and reveals substantial shifts and different vibrational modes between RaX2·H2O and RaX2·2H2O compared to BaX2·2H2O.

A series of ten uranium(III) complexes with cyclopentadienyl and monodentate phosphine ligands [UCp3(PR3)] with R = Me, Et, nPr, iPr, tBu, Ph, Cy, F and CF3 was investigated using density functional ...

Molecular imaging with analyte-responsive probes offers a powerful chemical approach to studying biological processes. Many reagents for bioimaging employ a fluorescence readout, but the relatively br...

Isostructural trivalent lanthanide and actinide amidinates bearing the N,N’-bis(isopropyl)benzamidinate (iPr2BA) ligand [LnIII/AnIII(iPr2BA)3] (Ln = La, Nd, Sm, Eu, Yb, Lu; An = U, Np) have been synthesized and characterized in both solid and solution states. All compounds were examined in the solid state utilizing single crystal X-ray diffraction (SC-XRD), revealing a notable deviation in the actinide series with shortened bond lengths compared to the trend in the lanthanide series, suggesting a nonionic contribution to the actinide–ligand bonding. Quantum-chemical bonding analysis further elucidated the nature of these interactions, highlighting increased covalency within the actinide series, as evidenced by higher delocalization indices and greater 5f orbital occupation, except for Th(III) and Pa(III), which demonstrated substantial 6d orbital occupancies. An in-depth paramagnetic NMR study in solution also sheds light on the covalent character of actinide–ligand bonding, with the separation of pseudocontact (PCS) and contact shift (FCS) contributions employing the Bleaney and Reilley method. This analysis unveiled significant contact contributions in the actinide complexes, indicating enhanced covalency in actinide–ligand bonding. To corroborate these observations, an accurate PCS calculation method based on the Kuprov equation, incorporating both the distribution of electronic spin density and magnetic susceptibility obtained from CASSCF calculations, was applied and compared with experimental values.

Novel tetravalent actinide (AnIV) compounds with the Schiff base ligand pyrophen, including the transuranium elements Np and Pu, are characterized in solid state and solution, as well as by quantum c...

Triplet nitrenes are highly reactive species and thus their isolation and characterization are challenging. Now, a bulky hydrindacene ligand has been used to stabilize a triplet arylnitrene synthesize...