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$\mathrm{L}{\mathrm{a}}_{0.4}\mathrm{C}{\mathrm{e}}_{0.6}\mathrm{C}{\mathrm{o}}_{2}{\mathrm{P}}_{2}$ represents a borderline case in the range of solid solutions formed in the pseudobinary system $\mathrm{LaC}{\mathrm{o}}_{2}{\mathrm{P}}_{2}\text{\ensuremath{-}}\mathrm{CeC}{\mathrm{o}}_{2}{\mathrm{P}}_{2}$. The material undergoes ferromagnetic ordering at \ensuremath{\sim}225 K followed by a structural collapse at \ensuremath{\sim}190 K, which leads to a strong suppression of magnetization. The structural phase transition manifests itself in a gradual decrease in the parameter $c$ and a relatively smaller increase of the parameter $a$ of the tetragonal lattice. Interestingly, a combination of magnetic measurements and nonpolarized and polarized neutron scattering experiments suggests that the structural collapse does not lead to an antiferromagnetically ordered state, observed in samples with the higher Ce content. On the contrary, $\mathrm{L}{\mathrm{a}}_{0.4}\mathrm{C}{\mathrm{e}}_{0.6}\mathrm{C}{\mathrm{o}}_{2}{\mathrm{P}}_{2}$ appears to enter a disordered, spin glass state, with gradual dissipation of the ferromagnetic ordering taking place simultaneously with the structural collapse, as evidenced by temperature-dependent measurements of the depolarization factor for a polarized neutron beam passing through the sample. The observed behavior is analogous to that reported for so-called reentrant spin glasses. In the present case, however, the appearance of the reentrant spin glass regime is caused not by tuning the chemical composition but by the structural phase transition. Electronic structure calculations confirm that the loss of magnetic ordering is caused by the subtle change to the density of states at the Fermi level due to the variation of the crystal structure of the material.

A series of f-block chromates, CsM(CrO

bibtex: ISI:000412043000020 bibtex\location:'1155 16TH ST, NW, WASHINGTON, DC 20036 USA',publisher:'AMER CHEMICAL SOC',type:'Article',affiliation:'Albrecht-Schmitt, TE (Reprint Author), Florida State Univ, Dept Chem & Biochem, Tallahassee, FL 32306 USA. Silver, Mark A.; Cary, Samantha K.; Arico, Alexandra A.; Galmin, Gregory A.; Wang, Jamie C.; Clark, Ronald J.; Chemey, Alexander; Eaton, Teresa M.; Marsh, Matthew L.; Seidler, Kevin; Galley, Shane S.; van de Burgt, Lambertus; Hobart, David E.; Hanson, Kenneth; Albrecht-Schmitt, Thomas E., Florida State Univ, Dept Chem & Biochem, Tallahassee, FL 32306 USA. Garza, Alejandro J.; Scuseria, Gustavo E., Rice Univ, Dept Chem, POB 1892, Houston, TX 77251 USA. Baumbach, Ryan E.; Chen, Kuan-Wen, Natl High Magnet Field Lab, Tallahassee, FL 32310 USA. Johnson, Jason A.; Gray, Ashley L., Florida State Univ, Environm Hlth & Safety, Tallahassee, FL 32306 USA. Van Cleve, Shelley M., Oak Ridge Natl Lab, Nucl Mat Proc Grp, One Bethel Valley Rd, Oak Ridge, TN 37830 USA. Gendron, Frederic; Autschbach, Jochen, Univ Buffalo State Univ New York, Dept Chem, Buffalo, NY 14260 USA. Maron, Laurent, Inst Natl Sci Appl, Lab Phys & Chim Nanoobjets, F-31077 Toulouse 4, France. Speldrich, Manfred; Koegerler, Paul, Rhein Westfal TH Aachen, Inst Anorgan Chem, D-52074 Aachen, Germany. Celis-Barros, Cristian; Paez-Hernandez, Dayan; Arratia-Perez, Ramiro, Univ Andres Bello, Fac Ciencias Exactas, Ctr Nanociencias Aplicadas, Republ 275, Santiago, Chile. Ruf, Michael, Bruker AXS, 5465 East Cheryl Pkwy, Madison, WI 53711 USA.','author-email':'albrecht-schinitt@chem.fsu.edu',da:'2018-12-05','doc-delivery-number':'FI5SB','funding-acknowledgement':'U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Heavy Elements Chemistry Program [DE-FG02-13ER16414, DE-SC0001136, DE-FG02-04ER15523]; Welch Foundation Chair [C-0036]; National Science Foundation [DMR-1157490, DGE-1449440]; State of Florida; U.S. Department of Energy; CBFO Fellowship Program (MAS) - U.S. Department of Energy','funding-text':'This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Heavy Elements Chemistry Program, under Award Numbers DE-FG02-13ER16414 (FSU), DE-SC0001136 (formerly DE-FG02-09ER16066) (FG & JA), and DE-FG02-04ER15523 (G.E.S). G.E.S. is a Welch Foundation Chair (Grant No. C-0036). The isotopes used in this research were supplied by the U.S. Department of Energy, Office of Science, by the Isotope Program in the Office of Nuclear Physics. The \textlessSUP\textgreater249\textless/SUP\textgreaterBk was provided to Florida State University by the Isotope Development and Production for Research and Applications Program through the Radiochemical Engineering and Development Center at Oak Ridge National Laboratory. Magnetization measurements using the VSM SQUID MPMS were performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation Cooperative Agreement No. DMR-1157490, the State of Florida, and the U.S. Department of Energy. This research is supported in part by an appointment to the CBFO Fellowship Program (MAS), sponsored by the U.S. Department of Energy and administered by the Oak Ridge Institute for Science and Education. Jamie Wang is supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1449440.','journal-iso':'J. Am. Chem. Soc.','keywords-plus':'VALENCE BASIS-SETS; ENERGY-ADJUSTED PSEUDOPOTENTIALS; MOLECULAR-ORBITAL METHODS; CRYSTAL-STRUCTURE; AB-INITIO; MAGNETIC-SUSCEPTIBILITY; COORDINATION GEOMETRY; PERTURBATION-THEORY; IONIC-RADII; PLUTONIUM','number-of-cited-references':'113',oa:'Bronze','orcid-numbers':'Kogerler, Paul/0000-0001-7831-3953 Gendron, Frederic/0000-0002-1896-3978 Hanson, Kenneth/0000-0001-7219-7808 Albrecht-Schmitt, Thomas/0000-0002-2989-3311 Chemey, Alexander/0000-0002-0679-7845 Paez, Dayan/0000-0003-2747-9982 Speldrich, Manfred/0000-0002-8626-6410 Celis-Barros, Cristian/0000-0002-4685-5229 Garza, Alejandro/0000-0001-6995-2833','research-areas':'Chemistry','researcherid-numbers':'Kogerler, Paul/H-5866-2013','times-cited':'5','unique-id':'ISI:000412043000020','usage-count-last-180-days':'8','usage-count-since-2013':'36','web-of-science-categories':'Chemistry, Multidisciplinary'\; International audience; The reaction of Bk-249(OH)(4) with iodate under hydro thermal conditions results in the formation of Bk(IO3)(3) as the major product with trace amounts of Bk(IO3)(4) also crystallizing from the reaction mixture. The structure of Bk(Io(3))(3) consists of nine-coordinate BO cations that are bridged by iodate anions to yield layers that are isomorphous with those found for Am-III, Cf-III, and with lanthanides that possess similar ionic radii. Bk(IO3)(4) was expected to adopt the same structure as M(IO3)(4) (M = Ce, Np, Pu), but instead parallels the structural chemistry of the smaller Zr-IV cation. Bk-III-O and Bk-IV-O bond lengths are shorter than anticipated and provide further support for a postcurium break in the actinide series. Photoluminescence and absorption spectra collected from single crystals of Bk(IO3)(4) show evidence for doping with Bkill in these crystals. In addition to luminescence from Bkul in the Bk(IO3)(4) crystals, a broad-band absorption feature is initially present that is similar to features observed in systems with intervalence charge transfer. However, the high-specific activity of Bk-249 (t(1/2) = 320 d) causes oxidation of Bk-III and only Bk-IV is present after a few days with concomitant loss of both the Bk-III luminescence and the broadband feature. The electronic structure of Bk(IO3)(3) and Bk(IO3)(4) were examined using a range of computational methods that include density functional theory both on clusters and on periodic structures, relativistic ab initio wave function calculations that incorporate spin orbit coupling (CASSCF), and by a full-model Hamiltonian with spin-orbit coupling and Slater-Condon parameters (CONDON). Some of these methods provide evidence for an asymmetric ground state present in Bk-IV that does not strictly adhere to Russel Saunders coupling and Hund's Rule even though it possesses a half-filled Sf(7) shell. Multiple factors contribute. to the asymmetry that include 5f electrons being present in microstates that are not solely spin up, spin-orbit coupling induced mixing of low-lying excited states with the ground state, and covalency in the Bk-IV-O bonds that distributes the 5f electrons onto the ligands. These factors are absent or diminished in other f(7) ions such as Gd-III or Cm-III.

The reaction of (248)CmCl3 with excess 2,6-pyridinedicarboxylic acid (DPA) under mild solvothermal conditions results in crystallization of the tris-chelate complex Cm(HDPA)3 · H2O. Approximately half of the curium remains in solution at the end of this process, and evaporation of the mother liquor results in crystallization of the bis-chelate complex [Cm(HDPA)(H2DPA)(H2O)2Cl]Cl·2H2O. (248)Cm is the daughter of the α decay of (252)Cf and is extracted in high purity from this parent. However, trace amounts of (249,250,251)Cf are still present in all samples of (248)Cm. During the crystallization of Cm(HDPA)3 · H2O and [Cm(HDPA)(H2DPA)(H2O)2Cl]Cl · 2H2O, californium(III) spontaneously separates itself from the curium complexes and is found doped within crystals of DPA in the form of Cf(HDPA)3. These results add to the growing body of evidence that the chemistry of californium is fundamentally different from that of earlier actinides.

A break in periodicity occurs in the actinide series between plutonium and americium as the result of the localization of 5f electrons. The subsequent chemistry of later actinides is thought to closely parallel lanthanides in that bonding is expected to be ionic and complexation should not substantially alter the electronic structure of the metal ions. Here we demonstrate that ligation of californium(III) by a pyridine derivative results in significant deviations in the properties of the resultant complex with respect to that predicted for the free ion. We expand on this by characterizing the americium and curium analogues for comparison, and show that these pronounced effects result from a second transition in periodicity in the actinide series that occurs, in part, because of the stabilization of the divalent oxidation state. The metastability of californium(II) is responsible for many of the unusual properties of californium including the green photoluminescence., The chemistry of the post-plutonium actinides is thought to resemble lanthanides in that bonding is primarily ionic. Here, the authors show that a californium(III) complex displays significantly different properties to those predicted for the free ion owing to a second break in actinide periodicity.