Potentiometric determination of stabilities of molybdenum(IV) and tungsten(VI) chelates

Metal assisted peptide bond hydrolysis: Chemistry, biotechnology and toxicological implications

“…The sizes of ionic radii of MoO 2− 4 and WO 2− 4 are similar, resulting in the formation of complexes with similar binding constants, as for EDTA [21]. However, the tungstate forms more labile chelates than molybdate with respect to the individual metal-ligand bonds, which is a likely cause for a lower rate constant for Gly Ser hydrolysis by WO 2− 4 [19,21,22]. The pD dependence of observed rate constant k obs for hydrolysis of dipeptides by oxo-metal anions has a bell-shaped profile, with the maximum at pD about 7.0 and 7.4 for the hydrolysis of Gly-Ser by MoO 2− 4 and VO 3− 4 , respectively (the reactions were investigated by NMR in D 2 O solutions).…”

“…The proposed reason for the lower constant rate for chromate is a smaller size of CrO 2− 4 compared to MoO 2− 4 , resulting in a higher solvation degree of CrO 2− 4 , impeding its coordination to the peptide [19]. The sizes of ionic radii of MoO 2− 4 and WO 2− 4 are similar, resulting in the formation of complexes with similar binding constants, as for EDTA [21]. However, the tungstate forms more labile chelates than molybdate with respect to the individual metal-ligand bonds, which is a likely cause for a lower rate constant for Gly Ser hydrolysis by WO 2− 4 [19,21,22].…”

Removal of Mo(VI) from aqueous solutions using sulfuric acid-modified cinder: kinetic and thermodynamic studies

“…However, a certain amount of Mo(VI) was found to be adsorbed on the adsorbent at high pH as seem from Figure 1, so there must be some other mechanisms playing a role. Since there is a reverse reaction between OH À and Mo(VI) from about pH 6-9 (Kula and Rabenstein 1966), Mo(VI) can exchange with OH À from the surface of adsorbent. In addition, the adsorption of Mo(VI) onto the tested cinder is well described by the Langmuir model ( Table 2).…”

Study on the Complexation of Molybdenum(VI) with Iminodiacetic Acid and Ethylenediamine‐N,N′‐diacetic Acid by Specific Ion Interaction and Debye‐Hückel Theories

“…According to our knowledge the dissociation equilibria of IDA and EDDA have been studied in different kinds of background electrolytes, 12,14,16,17 but there is no report about the ionic strength dependence of the dissociation constants of IDA. The following equilibria were studied for IDA and EDDA:…”