Vibrational spectra of the [UO2Cl4]2− and the [UO2Br4]2− ions

Lattice Solvent and Crystal Phase Effects on the Vibrational Spectra of UO2Cl42–

“…For compounds 1 – 6 , the uranyl symmetric stretch (ν 1 ) is a prominent signal in the Raman spectra located between 820 and 840 cm –1 (Table ) (Figure ). With the exception of compound 2 (823(1) cm –1 ), the observed symmetric stretching frequencies for compounds 1 – 6 agree well with the range of literature values for the UO 2 Cl 4 2– anion (831–842 cm –1 ). − The asymmetric stretching mode (ν 3 ) for complexes 1 – 6 appears as a strong absorption between 900 and 920 cm –1 (Table , Figure ). Similar to the symmetric vibrational mode, the observed frequency range for the asymmetric stretching frequency lies within the range of values previously reported for uranyl tetrachloride compounds (900–922 cm –1 ). − ,− The ∼20 cm –1 distribution of frequencies for both the symmetric and asymmetric stretching modes of compounds 1 – 6 is most likely due to variations in the crystallographic phase and the presence of lattice solvent, a theory that is addressed further below.…”

Structural and Vibrational Properties of U(VI)O2Cl42- and Pu(VI)O2Cl42- Complexes

“…Similarly, the ν 3 asymmetric stretch appears in the infrared spectra as a strong signal located at 907 ( U-Rb ), 922 ( U-Cs ), and 909 cm –1 ( U-Me 4 N ). These shifts for the symmetric and asymmetric stretches are similar to those previously observed for the UO 2 Cl 4 2‑ anion, which range from 831 to 842 cm –1 for ν 1 and 900 to 922 cm –1 for ν 3 . − ,,− , For compound U-Cs , in addition to the ν 1 signal at 832 cm –1 , a small peak is observed at 806 cm –1 corresponding to the 18 OU 16 O symmetric stretching frequency, which agrees with the degree of red shifting expected for the monoisotopically substituted uranyl moiety. , Isotopic shifting of the ν 1 symmetric stretching frequency has been previously observed in di-isotopically substituted 18 O species uranyl hydroxide species, U 18 O 2 (OH) n 2‑ n …”

“…Unlike the easily identifiable ν 1 symmetric and ν 3 asymmetric stretches of the actinyl moiety, the metal–chloride based vibrations are more difficult to definitively assign due to their close proximity to one another. Our tentative assignments discussed in the Supporting Information are based on the relative positions of the signals observed in previously reported AnO 2 Cl 4 2‑ compounds. ,,,,− ,, …”

“…In addition to single crystal X-ray diffractometry, the complexes presented herein have also been characterized using Raman and infrared spectroscopy. While the vibrational spectroscopy of U-Rb , − U-Cs , − U-Me 4 N , ,,,, and Pu-Cs (photoluminescence) has been previously investigated, to our knowledge this is the first instance where the Raman and infrared spectra of the plutonyl species have been collected and compared to their uranyl analogues. We have collected the Raman and infrared data for all six compounds to ensure similar conditions and allow for an accurate comparison between uranium and plutonium analogues.…”

Investigation of the Luminescence of [UO2X4]2– (X = Cl, Br) Complexes in the Organic Phase Using Time-Resolved Laser-Induced Fluorescence Spectroscopy and Quantum Chemical Simulations

“…The calculated frequencies have been compared with data from experimental Raman and IR measurements of different crystals or liquid samples of [R 4 N] 2 [UO 2 Cl 4 ]. − The computed symmetrical stretching frequency ν s for [Bu 4 N] 2 [UO 2 Cl 4 ] matches the value measured for the [Et 4 N] 2 [UO 2 Cl 4 ] crystal . For [Bu 4 N] 2 [UO 2 Cl 4 ], the gas-phase computed frequencies ν U–Cl , ν b , ν s , and ν a are overestimated by 12, 24, 36, and 26 cm –1 , respectively, with respect to the values measured in dichloromethane solution .…”