Studies on the composition and stability of uranyl, vanadyl and titanous complexes with some aminoacids

Farooq, Omar; Malik, Arshi; Ahmad, Naseer; Rahman, S. M. F.

doi:10.1016/s0022-0728(70)80169-3

Cited by 23 publications

(2 citation statements)

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“…On coordination to uranyl, the weaker glycolic acid gives lower stability constants (log β 1 ) 2.40) than the glycine complex (log β 1 ) 8.65). 46,[51][52][53][54] Fewer studies have been carried out on the uranyl-ODA system compared with the uranyl-IDA system, and small differences between constants obtained from this work and those in the literature probably arise from differences in experimental conditions. Di Bernardo et al 2 have given 10.03 as the log β value for a complex formulated as 2 (HODA)(ODA)] -.…”

Section: :2 Complexes (C)mentioning

confidence: 71%

“…The protonation and stability constants computed for all species are given in Table 3 and compared with values in the literature. [44][45][46][47] The log β values for the 1:1 IDA complex (9.90) are relatively high compared to the log β values for other 1:1 uranyl-carboxylate complexes (6.36 (oxalate), 1,48 5.43 (malonate), 49,50 and 8.65 (glycine) 51 ), suggesting that IDA behaves as a tridentate ligand in this 1:1 complex, coordinating through the two carboxylate groups and the central nitrogen atom. The value found here for the 1:1 complex is a little higher than the published ones, probably because different models were used in the computation.…”

Section: :2 Complexes (C)mentioning

confidence: 99%

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Solution Chemistry of Uranyl Ion with Iminodiacetate and Oxydiacetate: A Combined NMR/EXAFS and Potentiometry/Calorimetry Study

et al. 2003

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The solution chemistry of uranyl ion with iminodiacetate (IDA) and oxydiacetate (ODA) was investigated using NMR and EXAFS spectroscopies, potentiometry, and calorimetry. From the NMR and EXAFS data and depending on stoichiometry and pH, three types of metal:ligand complex were identified in solution in the pH range 3-7: 1:1 and 1:2 monomers; a 2:2 dimer. From NMR and EXAFS data for the IDA system and previous studies, we propose the three complex types are [UO(2)(IDA)(H(2)O)(2)], [UO(2)(IDA)(2)](2)(-), and [(UO(2))(2)(IDA)(2)(mu-OH)(2)](2)(-). From EXAFS spectroscopy, similar 1:1, 2:2, and 1:2 complexes are found for the ODA system, although (13)C NMR spectroscopy was not a useful probe in this system. For the 1:1 and 1:2 complexes in solution, EXAFS spectroscopy is ambiguous because the data can be fitted with either a long U-N/O(ether) value (ca. 2.9 A) suggesting 1,7-coordination of the ligand or a U-C interaction at a similar distance, consistent with terminal bidentate coordination. However, the NMR data of the IDA system suggest that 1,7-coordination is the more likely. The stability constants of the three complexes were determined by potentiometric titrations; the log beta values are 9.90 +/-, 16.42 +/-, and 10.80 +/- for the 1:1, 1:2, and 2:2 uranyl-IDA complexes, respectively, and 5.77 +/-, 7.84 +/-, and 4.29 +/- for the 1:1, 1:2, and 2:2 uranyl-ODA complexes, respectively. The thermodynamic constants for the complexes were calculated from calorimetric titrations; the enthalpy changes (kJ mol(-)(1)) and entropy changes (J K(-)(1) mol(-)(1)) of complexation for the 1:1, 1:2, and 2:2 complexes respectively are the following. IDA: 12 +/- 2, 230 +/- 8; 8 +/- 2, 151 +/- 9; -33 +/- 3, -283 +/- 11. ODA: 26 +/- 2, 198 +/- 12; 20 +/- 2, 106 +/- 8; -24 +/- 2; -219 +/- 8.

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Section: :2 Complexes (C)mentioning

confidence: 71%