Synthesis, crystal and molecular structure, and spectral properties of guanidinium salt of complex uranyl 2-methoxybenzoate

Fedoseev, A. M.; Gubanov, E. V.; Григорьев, М. С.; Yusov, A. B.

doi:10.1134/s1066362212040042

Cited by 4 publications

(3 citation statements)

References 4 publications

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“…For meta-methoxybenzoate, no comparable crystal structures for the uranium(VI) complexes have yet been reported unfortunately. Moreover, there are three reported crystal structures of U(VI) compounds embodying the [UO 2 (2-mba) 3 ] − unit complexes with small outer-sphere organic cations: (1) [C(NH 2 ) 3 ][UO 2 (2-mba) 3 ]·H 2 O( s ), (2) C 3 N 2 H 5 [UO 2 (2-mba) 3 ]·H 2 O( s ), and (3) CH 3 C 3 N 2 H 4 [UO 2 (2-mba) 3 ]·H 2 O( s ) where C(NH 2 ) 3 + , C 3 N 2 H 5 + , and CH 3 C 3 N 2 H 4 + represent the protonated guanidinium, imidazolium, and 1-methylimidazolium cations, respectively. In the last three crystalline uranium(VI) compounds, 2-mba ligands coordinate to the uranyl group in bidentate mode with 3:1 stoichiometry also, but the all carboxyl groups twist significantly in relation to the ligands’ benzene ring as a consequence of direct molecular interactions with the organic cations (e.g., formation of hydrogen bond and π-staking).…”

Section: Resultsmentioning

confidence: 99%

“…The peak position of the ν 3 vibration definitely reflects the 1:3 binding stoichiometry of uranyl to 2-mba ligands, since the IR-active ν 3 vibration generally shows the similar stepwise red-shift tendency to the Raman-active ν 1 vibration as complexation progresses 17 and it is comparable with the reported vibrations of other uranium(VI) tri-2-mba compounds having bidentate structures. 45,46 Finally, a relatively weak IR peak at 885 cm −1 is assumed to be a signal representing the anharmonic coupling of stretches of both uranyl and benzoate groups, 42−44 which is strongly observed in the Raman spectra.…”

Section: Vibrational Analysis Of the Na[uo 2 (2-mba) 3 ]• 12h 2 O(s) ...mentioning

confidence: 99%

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Thermodynamic, Spectroscopic, and Structural Study on a Sodium Uranyl Tri-2-Methoxybenzoate Dodecahydrate Coordination Compound with Considerably Low Solubility in Acidic Conditions

et al. 2022

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A spontaneous crystallization of an uranium(VI)organic coordination compound with sodium and 2-methoxybenzoate (2-mba) was observed in acidic solutions, and the solubility product, molecular vibrations, crystal structure, thermal stability, and emission properties of the atypically low-soluble U(VI) complex (Na[UO 2 (2-mba) 3 ]•12H 2 O(s)) were fully investigated for the first time. A long-term solubility experiment and speciation modeling gave a solubility product of log K s,0 = −12.18 ± 0.02 (T = 25 °C and I = 0.1 M NaClO 4 ), and vibrational analyses confirmed the overall molecular structure of complex and the frequencies of characteristic stretching motions of uranyl moiety as well. The crystal quality of Na[UO 2 (2-mba) 3 ]•12H 2 O(s) was improved by a digestion method, and X-ray diffraction analysis of the single crystalline specimen verified that the newly studied uranyl-organic compound contains one-dimensional channels with a diameter of 20 Å along the [001] direction; the sodium and water molecules are arranged in the channel structures. In the coordination environment around uranyl, three aromatic carboxylates are symmetrically bound in the equatorial plane of uranyl coplanarily, and the unit [UO 2 (2-mba) 3 ] − complexes are further extended along the plane to form the layered-morphologies. The three-dimensional packing of [UO 2 (2-mba) 3 ] − anions is driven by the parallel-displaced π-stacking of aromatic rings with a centroidcentroid distance of 3.7 Å. Additional thermogravimetric analysis confirmed that the Na[UO 2 (2-mba) 3 ]•12H 2 O(s) is stable up to 250 °C, and dehydration and release of the organic ligand were subsequently observed beyond that temperature. Photoluminescence spectrum of the Na[UO 2 (2-mba) 3 ]•12H 2 O(s) clearly displayed the characteristic U(VI) emission, and a band spacing between the ground electronic states of U(VI) uranyl was evaluated to be 831 ± 14 cm −1 . Such detailed characterization of the unique Na[UO 2 (2-mba) 3 ]•12H 2 O(s) is advancing upon a systematic understanding of the structural effects of the aromatic model ligands on U(VI) complexation, with relevance to the environmental chemistry of U(VI) and crystal engineering for development of diverse uranyl-organic frameworks.

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Section: Resultsmentioning

confidence: 99%

Section: Vibrational Analysis Of the Na[uo 2 (2-mba) 3 ]• 12h 2 O(s) ...mentioning

confidence: 99%

Thermodynamic, Spectroscopic, and Structural Study on a Sodium Uranyl Tri-2-Methoxybenzoate Dodecahydrate Coordination Compound with Considerably Low Solubility in Acidic Conditions

et al. 2022

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“…Such a thermodynamic tendency accords closely with the reported structural deformation of the solid uranyl 2-methoxybenzoate complexes. In the two previous studies, , crystalline 1:3 uranyl 2-methoxybenzoates with some organic cations were synthesized, and their molecular structures were identified by single-crystal X-ray diffraction. In the solid uranyl compounds, 2-methoxybenzoate anions coordinate to the uranyl group in the bidentate mode, and the carboxyl groups twist considerably in relation to the plane of the benzene ring (maximum torsion angle = 48.7°).…”

Section: Resultsmentioning

confidence: 99%

Spectroscopic Study on Aqueous Uranyl(VI) Complexes with Methoxy- and Methylbenzoates: Electronic and Steric Effects of the Substituents

Choi

Yun

2020

Inorg. Chem.

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Aqueous complexation of uranyl(VI) ions with methoxy- and methylbenzoates in 0.1 M NaClO4 solutions was studied by means of UV–vis absorption and Raman spectroscopy. The predominance of 1:1 complexation (uranyl to ligand) was verified for all uranyl carboxylates under acidic conditions (−log [H+] < 3.2), and absorption spectra, stability constants, and symmetric stretching frequencies of the uranyl group of the complexes were determined for the first time. For meta- and para-substituted benzoates, a linear free energy relationship (LFER) was observed between the equilibrium constants for the protonation (log βP) and uranyl complexation (log βU) reactions, and the electronic effects of the substituents were successfully described by the Hammett equation. In the case of ortho-substituted benzoates, the stability constant of uranyl 2-methoxybenzoate is slightly lower than the LFER trend, which is generally explained by the destabilization of cross-conjugation in the uranyl complex due to the steric hindrance between the reaction center and adjacent methoxy group. On the contrary, the stability constant of uranyl 2-methylbenzoate is comparable to the LFER trend, implying that the steric effect is relatively insignificant for the smaller methyl group. The utility of such thermodynamic correlations between the uranyl-substituted benzoates is useful for the molecular understanding and predictive modeling of chemical interactions between actinyl(VI) ions and various organic carboxyl groups.

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Uranium(VI) complex with m-hydroxybenzoic acid. Synthesis, crystal structure, and spectral properties

et al. 2014

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Synthesis, crystal and molecular structure, and spectral properties of guanidinium salt of complex uranyl 2-methoxybenzoate

Cited by 4 publications

References 4 publications

Thermodynamic, Spectroscopic, and Structural Study on a Sodium Uranyl Tri-2-Methoxybenzoate Dodecahydrate Coordination Compound with Considerably Low Solubility in Acidic Conditions

Thermodynamic, Spectroscopic, and Structural Study on a Sodium Uranyl Tri-2-Methoxybenzoate Dodecahydrate Coordination Compound with Considerably Low Solubility in Acidic Conditions

Spectroscopic Study on Aqueous Uranyl(VI) Complexes with Methoxy- and Methylbenzoates: Electronic and Steric Effects of the Substituents

Uranium(VI) complex with m-hydroxybenzoic acid. Synthesis, crystal structure, and spectral properties

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