Steric effects on uranyl complexation: synthetic, structural, and theoretical studies of carbamoyl pyrazole compounds of the uranyl(VI) ion

Das, D., Kannan, S., Maity, D. K. and Drew, M. G. B. (2012) Steric effects on uranyl complexation: synthetic, structural, and theoretical studies of carbamoyl pyrazole compounds of the uranyl(VI) ion. Inorganic Chemistry, 51 (8). pp. 4869-4876. ISSN 0020-1669 doi: 10.1021/ic300398a

Abstract/Summary

New bifunctional pyrazole based ligands of the type [C3HR2N2CONR'] (where R = H or CH3; R' = CH3, C2H5, or (C3H7)-C-i) were prepared and characterized. The coordination chemistry of these ligands with uranyl nitrate and uranyl bis(dibenzoyl methanate) was studied with infrared (IR), H-1 NMR, electrospray-mass spectrometry (ES-MS), elemental analysis, and single crystal X-ray diffraction methods. The structure of compound [UO2(NO3)(2)(C3H3N2CON{C2H5}(2))] (2) shows that the uranium(VI) ion is surrounded by one nitrogen atom and seven oxygen atoms in a hexagonal bipyramidal geometry with the ligand acting as a bidentate chelating ligand and bonds through both the carbamoyl oxygen and pyrazolyl nitrogen atoms. In the structure of [UO2(NO3)(2)(H2O)(2)(C5H7N2CON {C2H5}(2))(2)], (5) the pyrazole figand acts as a second sphere ligand and hydrogen bonds to the water molecules through carbamoyl oxygen and pyrazolyl nitrogen atoms. The structure of [UO2(DBM)(2)C3H3N2CON{C2H5}(2)] (8) (where DBM = C6H5COCHCOC6H5) shows that the pyrazole ligand acts as a monodentate ligand and bonds through the carbamoyl oxygen to the uranyl group. The ES-MS spectra of 2 and 8 show that the ligand is similarly bonded to the metal ion in solution. Ab initio quantum chemical studies show that the steric effect plays the key role in complexation behavior.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/30371
Item Type	Article
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Publisher	American Chemical Society
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