Lester R. Morss

The chemistry of the actinide elements

One.- 8. Americium.- 9. Curium.- 10. Berkelium.- 11. Californium.- 12. Einsteinium.- 13. Transeinsteinium Elements.- Two.- 14. Summary and comparative aspects of the actinide elements.- 15. Spectra and electronic structures of free actinide atoms and ions.- 16. Optical spectra and electronic structure of actinide ions in compounds and in solution.- 17. Thermodynamic properties.- 18. Magnetic properties.- 19. The metallic state.- 20. Structural chemistry.- 21. Solution chemistry and kinetics of ionic reactions.- 22. Organoactinide chemistry: properties of compounds having metal-carbon bonds only to ?-bonded ligands.- 23. Organoactinide chemistry: properties of compounds with actinide-carbon, actinide-transition-metal ? bonds.- 24. Future elements (including superheavy elements).- Appendix I.- Nuclear spins and moments of the actinides.- Appendix II.- Nuclear properties of actinide nuclides.- Author Index (Volumes 1 and 2).- Subject Index (Volumes 1 and 2).

Synthesis of lanthanide and actinide compounds

Actinide Hydrides.- Lanthanide Fluorides.- Actinide Fluorides.- Binary Lanthanide (III) Halides, MX, (X = Cl, Br, I).- Complex Lanthanide (III) Chlorides, Bromides and Iodides.- Conproportionation Routes to Reduced Lanthanide Halides.- Action of Alkali Metals on Lanthanide (III) Halides: an Alternative to the Conproportionation Route to Reduced Lanthanide Halides.- The Binary Lanthanide Oxides: Synthesis and Identification.- Polynary Alkali-Metal Lanthanide Oxides.- Synthesis of Actinide Oxides.- Chemical (Vapour Phase) Transport in Lanthanide and Actinide Oxide and Oxychloride Chemistry.- I. Tantalates, Oxychlorotantalates and Niobates.- II. Thorium Tantalates and Niobates.- Synthesis of Phosphates, Carbonates, Titanates and other Lanthanide and Actinide Elements.- Preparation of Rare Earth Sulfides and Selenides.- Synthesis of f-Element Pnictides.

Aqueous complexation of trivalent lanthanide and actinide cations by N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine

Abstract The aqueous complexation reactions of trivalent lanthanide and actinide cations with the hexadentate ligand N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) have been characterized using potentiometric and spectroscopic techniques in 0.1 M NaClO4. At 25°C, the stability constant of Am(TPEN)3+ is two orders of magnitude larger than that of Sm(TPEN)3+, reflecting the stronger interactions of the trivalent actinide cations with softer ligands as compared to lanthanide cations.

Facile synthesis of UCl4 and ThCl4, metallothermic reductions of UCl4 with alkali metals and crystal structure refinements of UCl3, UCl4 and Cs2UCl6

Abstract Uranium and thorium tetrachloride (UCl 4 and ThCl 4 ) were obtained via the ammonium chloride route from UH 3 and thorium metal respectively, with the ternary chlorides (NH 4 ) 2 UCl 6 and (NH 4 ) 2 ThCl 6 acting as intermediates. The crystal structure of UCl 4 was refined ( R = 0.031, R w = 0.026). Cs 2 UCl 6 and Cs 2 ThCl 6 were synthesized, their lattice constants refined from powder data, and the crystal structure of Cs 2 UCl 6 refined from single-crystal data ( R = 0.066, R w = 0.052). Some indication for stacking disorder in the [00.1] direction was found. Metallothermic reductions of UCl 4 with lithium and sodium led to UCl 3 whose crystal structure was also refined ( R = 0.029, R w = 0.023). Potassium reduced UCl 4 to K 2 UCl 5 . No further reduction could be detected.

Thermochemical regularities among lanthanide and actinide oxides

Abstract A systematic treatment of the thermochemical properties of binary and complex oxides of the lanthanides and actinides in terms of other wellcharacterized species and thermochemical cycles is given in this paper. Since the trivalent lanthanides provide a reference series with which the lanthanide and actinide sesquioxides can be compared, the trivalent ion energetics are considered first. Recent interest in monoxides, prompted by high pressure synthesis of lanthanide monoxides and interest in divalent actinide metals and oxides, has led us to include a treatment of the relative stabilities of monoxides and sesquioxides. The important tetravalent state is viewed from the perspective of the dioxides as well as the perovskites BaMO3. Since there are no higher valent lanthanides, systematic trends in pentavalent and hexavalent complex actinide oxides are not treated in this review.

SYNTHESES AND CRYSTAL STRUCTURES OF M(NO3)2(TPEN)NO3.3H2O (M = LA, TB), RARE EARTH COMPLEXES WITH STRONG M-N BONDS

Abstract The compounds [M(NO3)2(tpen)][NO3]·3H2O with M=La, Nd, Eu, Tb and Y have been synthesized. Single crystals have been grown of the compounds with M=La and Tb from water–ethanol solution. Their crystal structures have been determined. The compounds are isostructural; the metals are ten-fold coordinated, with six nitrogens from one tpen ligand and four oxygens from two nitrates. Growth of crystals with nitrogen coordinated to rare earths in water-containing solution is unusual and indicates that tpen is a good nitrogen donor even with hard cations.

Cerium, uranium, and plutonium behavior in glass-bonded sodalite, a ceramic nuclear waste form.

Abstract Glass-bonded sodalite is being developed as a ceramic waste form (CWF) to immobilize radioactive fission products, actinides, and salt residues from electrometallurgical treatment of spent nuclear reactor fuel. The CWF consists of about 75 mass% sodalite, 25 mass% glass, and small amounts of other phases. This paper presents some results and interpretation of physical measurements to characterize the CWF structure, and dissolution tests to measure the release of matrix components and radionuclides from the waste form. Tests have been carried out with specimens of the CWF that contain rare earths at concentrations similar to those expected in the waste form. Parallel tests have been carried out on specimens that have uranium or plutonium as well as the rare earths at concentrations similar to those expected in the waste forms; in these specimens UCl3 forms UO2 and PuCl3 forms PuO2. The normalized releases of rare earths in dissolution tests were found to be much lower than those of matrix elements (B, Si, Al, Na). When there is no uranium in the CWF, the release of cerium is two to ten times lower than the release of the other rare earths. The low release of cerium may be due to its tetravalent state in uranium-free CWF. However, when there is uranium in the CWF, the release of cerium is similar to that of the other rare earths. This trivalent behavior of cerium is attributed to charge transfer or covalent interactions among cerium, uranium, and oxygen in (U,Ce)O2.

Summary and Comparative Aspects of the Actinide Elements

This chapter is intended to provide a unified view of selected aspects of the physical, chemical, and biological properties of the actinide elements. The f-block elements have many unique features, and a comparison of the lanthanide and actinide transition series provides valuable insights into the properties of both. Comparative data are presented on the electronic configurations, oxidation states, redox potentials, thermochemical data, crystal structures, and ionic radii of the actinide elements, together with a miscellany of topics related to their environmental and health aspects. Much of this material is assembled in tabular and graphical form to facilitate rapid access. Many of the topics covered in this chapter, and some that are not discussed here, are the subjects of subsequent chapters of this work, and these may be consulted for more comprehensive treatments. This chapter provides a welcome opportunity to discuss the biological and environmental aspects of the actinide elements, subjects that were barely mentioned in the first edition of this work but have assumed great importance in recent times.

Thermodynamics of actinide perovskite-type oxides. II: Enthalpy of formation of Ca3UO6, Sr3UO6, Ba3UO6, Sr3NpO6, and Ba3NpO6

Abstract The molar enthalpies of formation ΔfHmo of several ternary oxides (ordered perovskites) of hexavalent uranium and neptunium with alkaline earths have been determined at 298.15 K. The results for ΔfHmo/(kJ·mol−1) are as follows: Ca3UO6, −(3301.9±4.9); Sr3UO6, −(3262.6±4.4); Ba3UO6, −(3210.7±5.8); Sr3NpO6, −(3125.3±5.8); and Ba3NpO6, −(3086.0±7.7). The stabilities of these complex oxides with respect to the parent binary oxides are discussed. These results are compared with those found for related complex oxides.

Powder neutron diffraction and magnetic susceptibility of 248CmO2

Abstract We report the first neutron diffraction experiments on a sample of approximately 55 mg of CmO2, using the rare isotope 248Cm. Preparative techniques have assured that the sample is close to stoichiometry and X-ray patterns show only the expected f.c.c. lines. The neutron diffraction experiments confirm that the sample is nearly stoichiometric and rule out the possibility that the oxygen atoms form a superlattice to accommodate a mixture of Cm3+ and Cm4+ ions. Magnetic susceptibility measurements give a μeff value of (3.36 ± 0.06)μB for the effective paramagnetic moment, consistent with many other determinations of this property in Cm(IV) compounds, which have been interpreted in the past as indicating substantial Cm3+ impurity. In view of the contradiction between bulk susceptibility on the one hand and thermogravimetric and diffraction results on the other hand, we suggest that a re-evaluation of the electronic ground states in the actinide dioxides may be needed. Some other contradictory experimental results are given.