The resonance Raman effect of dicaesium uranyl tetrachloride in dimethyl sulfoxide

Tetrahalide Complexes of the [U(NR)2]2+ Ion: Synthesis, Theory, and Chlorine K-Edge X-ray Absorption Spectroscopy

“…To obtain solid-state molecular structure information on the neutral bis(methyl) imido uranium(VI) complex 8, 1,2bis(dimethylphosphino)ethane (dmpe) was added to a THF solution of complex 7. After separating a white precipitate that forms during the course of the reaction, the dmpe-adduct U(NMe) 2 I 2 (dmpe)(THF) (9) was isolated in near-quantitative yield (Scheme 1). This species was characterized by NMR spectroscopy, elemental analysis, and a single-crystal XRD experiment.…”

“…The volume of the solution was then reduced to approximately 10 mL, layered with an equal amount of diethyl ether, and cooled to −25 °C overnight to yield a dark red microcrystalline material that was rinsed with diethyl ether and dried in vacuo. The mother liquor was evaporated to dryness, reconstituted in a minimal amount of CH 2 Cl 2 , and again layered with diethyl ether to provide a second crop of crystalline material (total 3.62 g, 79% yield) after being cooled to −25 °C for 18 h. Synthesis of U(NMe) 2 I 2 (THF) 3 (8) and U(NMe) 2 I 2 (dmpe)(THF) (9). The following procedure is representative for the synthesis of complexes 8 and 9.…”

“…Theoretical and experimental studies on the uranyl ion, [UO 2 ] 2+ , have provided foundational models for understanding electronic structure and bonding in molecular actinide science. − Of particular interest are their relevance to understanding the environmental speciation of [UO 2 ] 2+ , its role in nuclear fuel reprocessing schemes, and its potential as a photocatalyst for solar fuel formation. − In the course of studying [UO 2 ] 2+ , the series of dianionic uranyl(VI) tetrahalides[UO 2 X 4 ] 2– (X = Cl, Br, I)have emerged as popular analytes for spectroscopic and computational studies. − ,− These highly symmetric D 4 h compounds are attractive because they can be prepared in high yields, can be isolated as large single crystals, and are air and moisture stable. Of equal importance, the tetrahalide derivatives can be used as convenient aqueous and nonaqueous starting materials in uranium(VI) synthetic schemes. − …”

Detection and identification of solids, surfaces, and solutions of uranium using vibrational spectroscopy

“…As a result, both resonance Raman spectroscopy, a method where excitation energies are similar in energy to electronic transitions in a molecule are utilized, and surface-enhanced Raman scattering (SERS), a method whereby Raman signals can be increased by 6–8 orders of magnitude via interactions with metallic nanostructures, are useful for detecting uranium species. Resonance Raman spectroscopy was applied to develop Raman excitation profiles (REPs) for uranyl nitrate [260,261], acetate [262], chloride [263] and formate [260] in dimethyl sulfoxide (DMSO). As shown in Fig.…”

“…For instance, the probability of observing uranyl nitrate in an excited state increases as the number of ligands increases from 2 (UO 2 (NO 3 ) 2 ) to 3 (RbUO 2 (NO 3 ) 3 ). This causes the vibrational frequency to blue-shift from 703 to 740 cm −1 (Δν 1 = 37 cm −1 ) [260,261,263]. As a comparison, the vibrational frequencies of ground state species red-shift by 1 cm −1 , that is, from 835 to 834 cm −1 (Δν 1 = −1 cm −1 ) when the number of coordinating ligands increase from 2 to 3.…”