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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(DOPOq)2(NO3)(py) (DOPOq=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. Computational analysis of the electronic structure of the complex reveals that the CfIII–ligand interactions are largely ionic. [ABSTRACT FROM AUTHOR]

The merging of small‐scale syntheses and rapid crystallization methods have provided access to crystalline samples of berkelium (Z=97) and californium (Z=98) coordination complexes and compounds that can be interrogated with a suite of spectroscopic tools and structural elucidation approaches that have come online over the last 20 years. The combination of this experimental data with relativistic theoretical methods that capture the effects of spin‐orbit coupling and scalar relativistic effects have allowed us to understand the electronic structure of berkelium and californium compounds at a level of detail that was not previously possible. The harbinger of this new era of post‐curium chemistry was the synthesis and characterization of [Cf{B6O8(OH)5}]. This compound possesses a structure type that is distinct from earlier actinide borates, a reduction in coordination number for californium, contracted Cf−O bond lengths, a substantially reduced magnetic moment with respect to the calculated free‐ion moment and, most importantly, vibronically coupled broadband photoluminescence. Ligand‐field analysis also showed that the splitting of the ground state was larger than typically found in the f‐block elements, and when taken together places its overall electronic structure as a hybrid of d‐ and f‐block components. The discovery of the unusual properties of this compound has led to the development of large families of 4f and 5f coordination complexes, in an effort to uncover the underlying origin of the electronic structure oddities, and whether there really is a sharp onset of these changes at californium. This in turn pushed the development of far more challenging berkelium chemistry (from a radiologic standpoint) because the half‐life of the isotopes decreases from 351 years for 249Cf to 330 days for 249Bk. This short review details some of the chemistry that has been reported over the last 15 years, and its consequences for understanding the periodic table. [ABSTRACT FROM AUTHOR]

[M(EtBTP)3][BPh4]3⋅3 CH3CN (M=Nd, Am; EtBTP=2,6‐bis(5,6‐diethyl‐1,2,4‐triazin‐3‐yl)pyridine) have been synthesized from reactions of MCl3⋅n H2O with EtBTP in acetonitrile followed by anion metathesis. Structural analysis reveals that these compounds contain M3+ cations bound by tridentate EtBTP ligands to create a tricapped trigonal prismatic geometry around the metal centers. Collection of high‐resolution, single‐crystal X‐ray diffraction data also allowed reduction in bond lengths esd's, such that a slight contraction of Δ=0.0158(18) Å in the Am−N versus Nd−N bond lengths was observed, even though these cations ostensibly have matching ionic radii. Theoretical evaluation revealed enhanced metal–ligand bonding through back donation in the [Am(EtBTP)3]3+ complex that is absent in [Nd(EtBTP)3]3+. Actinides versus lanthanides! Comparison of the NdIII and AmIII tris‐triazinyl complexes has revealed the nature of the selectivity for AmIII over lanthanides (see scheme). Theoretical evaluation revealed enhanced metal–ligand bonding through back donation in the [Am(EtBTP)3]3+ complex that is absent in [Nd(EtBTP)3]3+. [ABSTRACT FROM AUTHOR]

It is shown that UVO2+ ions can reside at UVIO22+ lattice sites during mild reduction and crystallization process under solvothermal conditions, yielding a complicated and rare mixed-valent uranium phosphonate compound that simultaneously contains UIV, UV, and UVI. The presence of uranium with three oxidation states was confirmed by various characterization techniques, including X-ray crystallography, X-ray photoelectron, electron paramagnetic resonance, FTIR, UV/Vis-NIR absorption, and synchrotron radiation X-ray absorption spectroscopy, and magnetism measurements. [ABSTRACT FROM AUTHOR]

Cooperative performance of mixed-valent Eu2+/Eu3+ in single-compound phosphors offers significant advantages in color rendering and luminescence efficiency, but their synthesis is challenging because of Eu2+ oxidation. Using the tunable nature of the metal-ion nodes in metal-organic frameworks (MOFs), we present an in situ reduction and crystallization route for preparing MOFs and doping Eu2+/Eu3+ with a controlled ratio. These materials exhibit rich photoluminescence, including intrinsic- and sensitized-emissions of Eu2+ and Eu3+, and long-lived luminescence from charge transfer. Color rendering can be easily achieved by fine-tuning the valence states of Eu. A linear relation between temperature and the intensity ratio of Eu2+/Eu3+ emissions provides outstanding properties for applications as self-calibrated luminescent thermometers with a wide working temperature range. Further incorporation of Tb3+ into the MOFs results in white light, utilizing all Eu2+,Tb3+, and Eu3+ emissions in a single crystalline lattice. [ABSTRACT FROM AUTHOR]

The limited long-term hydrolytic stability of rapidly emerging 3D-extended framework materials (MOFs, COFs, MOPs, etc.) is still one of major barriers for their practical applications as new solid-state electrolytes in fuel cells. To obtain hydrolytically stable materials, two H2PO4−-exchanged 3D inorganic cationic extended frameworks (CEFs) were successfully prepared by a facile anion-exchange method. Both anion-exchanged CEFs (YbO(OH)P and NDTBP) show significantly enhanced proton conductivity when compared with the original materials (YbO(OH)Cl and NDTB) with an increase of up to four orders-of-magnitude, reaching 2.36×10−3 and 1.96×10−2 S cm−1 at 98 % RH and 85 °C for YbO(OH)P and NDTBP, respectively. These values are comparable to the most efficient proton-conducting MOFs. In addition, these two anion-exchanged materials are stable in boiling water, which originates from the strong electrostatic interaction between the H2PO4− anion and the cationic host framework, showing a clear advance over all the acid-impregnated materials (H2SO4@MIL-101, H3PO4@MIL-101, and H3PO4@Tp-Azo) as practical solid-state fuel-cell electrolytes. This work offers a new general and efficient approach to functionalize 3D-extended frameworks through an anion-exchange process and achieves water-stability with ultra-high proton conductivity above 10−2 S cm−1. [ABSTRACT FROM AUTHOR]

The reactions of trivalent lanthanides and actinides with molten boric acid in high chloride concentrations result in the formation of M4[B16O26(OH)4(H2O)3Cl4] (M=Sm, Eu, Gd, Pu, Am, Cm, Cf). This cubic structure type is remarkably complex and displays both chirality and polarity. The polymeric borate network forms helical features that are linked via two different types of nine-coordinate f-element environments. The f-f transitions are unusually intense and result in dark coloration of these compounds with actinides. [ABSTRACT FROM AUTHOR]

Highlights from the article: Keywords: actinides; berkelium complexation; californium complexation; coordination chemistry B Our understanding of the chemistry of berkelium and californium has remained elusive b because of the dearth of modern structural and spectroscopic data as well as the absence of high-level quantum mechanical theory that captures relativistic effects. Coordination chemistry, actinides, berkelium complexation, californium complexation.

It is shown that UVO2+ ions can reside at UVIO22+ lattice sites during mild reduction and crystallization process under solvothermal conditions, yielding a complicated and rare mixed-valent uranium phosphonate compound that simultaneously contains UIV, UV, and UVI. The presence of uranium with three oxidation states was confirmed by various characterization techniques, including X-ray crystallography, X-ray photoelectron, electron paramagnetic resonance, FTIR, UV/Vis-NIR absorption, and synchrotron radiation X-ray absorption spectroscopy, and magnetism measurements. [ABSTRACT FROM AUTHOR]