Electrochemical Studies of Selected Lanthanide and Californium Cryptates.

Efforts to quantitatively reduce Cf → Cf in solution as well as studies of its cyclic voltammetry have been hindered by its scarcity, significant challenges associated with manipulating an unusually intense γ emitter, small reaction scales, the need for nonaqueous solvents, and its radiolytic effects on ligands and solvents. In an effort to overcome these impediments, we report on the stabilization of Cf by encapsulation in 2.2.

Synthesis, Spectroscopy, and Theoretical Details of Uranyl Schiff-Base Coordination Complexes.

Two uranyl Schiff-base coordination complexes, and {L = ,'-bis[(4,4'-diethylamino)salicylidene]-1,2-phenylenediamine}, have been synthesized that feature a rigid phenyl backbone. These complexes have been characterized by structural, spectroscopic, and theoretical analysis to offer an electronic structure basis to explain the bonding parameters and stability. Single-crystal X-ray analysis reveals that adopts the typical "soft taco confirmation" characteristic of uranyl salophen complexes, whereas features an unusual neutral ligand coordination that contains an internal hydrogen bond between the phenol and imine.

Experimental and Theoretical Comparison of Transition-Metal and Actinide Tetravalent Schiff Base Coordination Complexes.

A series of homoleptic tetravalent transition-metal and actinide Schiff-base coordination complexes, ML {M = Zr, Hf, Th, U; L = N, N'-bis[(4,4'-diethylamino)salicylidene]-1,2-phenylenediamine}, have been synthesized that feature a rigid phenyl backbone. These complexes create the opportunity for comparing a series of complexes containing metal cations in the formal IV+ oxidation state by structural, spectroscopic, and theoretical analysis that also incorporate the previously reported Ce(IV) and Pu(IV) analogues. X-ray crystallographic analysis reveals that all complexes are isomorphous and feature a co-facial ligand geometry.

Schiff-base coordination complexes with plutonium(iv) and cerium(iv).

PuL and CeL (L = N,N'-bis[(4,4'-diethylamino)salicylidene]-1,2-phenylenediamine) have been synthesized, and characterized by single crystal X-ray diffraction, UV/vis/NIR spectroscopy, and cyclic voltammetry. These studies reveal the enhanced stabilization of Pu(iv) versus Ce(iv) with this Schiff base, and quasi-reversible redox behaviour only with the plutonium complex.

Incipient class II mixed valency in a plutonium solid-state compound.

Electron transfer in mixed-valent transition-metal complexes, clusters and materials is ubiquitous in both natural and synthetic systems. The degree to which intervalence charge transfer (IVCT) occurs, dependent on the degree of delocalization, places these within class II or III of the Robin-Day system. In contrast to the d-block, compounds of f-block elements typically exhibit class I behaviour (no IVCT) because of localization of the valence electrons and poor spatial overlap between metal and ligand orbitals.

Electronic Structure and Properties of Berkelium Iodates.

The reaction of Bk(OH) with iodate under hydrothermal conditions results in the formation of Bk(IO) as the major product with trace amounts of Bk(IO) also crystallizing from the reaction mixture. The structure of Bk(IO) consists of nine-coordinate Bk cations that are bridged by iodate anions to yield layers that are isomorphous with those found for Am, Cf, and with lanthanides that possess similar ionic radii. Bk(IO) was expected to adopt the same structure as M(IO) (M = Ce, Np, Pu), but instead parallels the structural chemistry of the smaller Zr cation.

Characterization and thermogravimetric analysis of lanthanide hexafluoroacetylacetone chelates.

This work reports the thermodynamic characterizations of organometallic species as a vehicle for the rapid separation of volatile nuclear fission products via gas chromatography due to differences in adsorption enthalpy. Because adsorption and sublimation thermodynamics are linearly correlated, there is considerable motivation to determine sublimation enthalpies. A method of isothermal thermogravimetric analysis, TGA-MS and melting point analysis are employed on thirteen lanthanide 1,1,1,5,5,5-hexafluoroacetylacetone complexes to determine sublimation enthalpies.

Characterization of berkelium(III) dipicolinate and borate compounds in solution and the solid state.

Berkelium is positioned at a crucial location in the actinide series between the inherently stable half-filled 5f(7) configuration of curium and the abrupt transition in chemical behavior created by the onset of a metastable divalent state that starts at californium. However, the mere 320-day half-life of berkelium's only available isotope, (249)Bk, has hindered in-depth studies of the element's coordination chemistry. Herein, we report the synthesis and detailed solid-state and solution-phase characterization of a berkelium coordination complex, Bk(III)tris(dipicolinate), as well as a chemically distinct Bk(III) borate material for comparison.