ABSTRACT
The synthesis and structures of the homoleptic hexanitrato complexes of Am(III) and Cm(III), [(CH3)4N]2KAn(NO3)6 are reported. These compounds form a double perovskite structure type, A2B'BX6, crystallizing in the cubic space group Fm3Ìm. Their electronic properties, as calculated using the Quantum Theory of Atoms in Molecules, are reported and compared to their lanthanide homologues Eu(III) and Gd(III).
ABSTRACT
In efforts to study the periodic chemical properties of the rare earth elements and their structural chemistry, a hybrid double perovskite phase A2B'BX6 with the formula ((CH3)4N)2KLn(NO3)6 (Ln = La-Lu, Y ex. Pm) was synthesized that crystallizes in the cubic space group, Fm3Ì m. This series was obtained via evaporative crystallization from a mixture of Ln(NO3)3, KNO3, and (CH3)4N·NO3 in a 1:1:2 ratio from either H2O or 4.0 M HNO3. In this double perovskite structure, the B site containing the lanthanide ion is coordinated by six bidentate nitrate ligands, with the distal NâO oxygen atoms coordinating the potassium on the B' site in an octahedral six-coordinate environment. The two remaining charge-compensating (CH3)4N+ cations occupy the interstitial voids in the lattice on the A site. This periodic series was characterized via single-crystal X-ray diffraction, powder X-ray diffraction, IR, and Raman spectroscopy. Emission spectra of the Eu complex indicate a phase transition to trigonal symmetry upon cooling. This series is unique as it represents a rare isostructural series spanning the entirety of the rare earth elements excluding promethium with homoleptic 12-coordinate rare earth metal ions.
ABSTRACT
Hydrofluxes are hydrated salts with melting points well below that of the dehydrated salt and boiling points well above that of water, affording a reaction medium, in which mild temperatures and pressures can be accessed for the synthesis of materials. Herein, the use of alkali metal hydroxide hydrofluxes for the synthesis of single crystal α-Na2 NpO4 is described, and the single crystal X-ray structure of α-Na2 NpO4 , along with its X-ray absorption spectra and vibrational spectra, is reported. The ability to synthesize complex oxides of the actinides, in particular, transuranium materials, under mild conditions will serve to advance our ability to explore the structure-property relationships of the f elements.