Manganese stability constant data

Mixed donor ligands. AG°, AH°, and AS° values for the formation of complexes between asparaginate and Mn2+ as well as H+, Fe2+, Co2+, Ni2 +, and Zn2+ in aqueous solution at 25°C have been reported.93 Cytostatic Hadacidin, JV-formyl-JV-hydroxyglycine (HAD), forms the complex Mn(HAD) for which spectroscopic and stability constant data have been reported.94 Manganese(n) complexes of human serum albumin have also been studied.95... 

The formation of the hydrolysis species of manganese(II) and manganese(III) can be described by reaction (2.5) (M = Mn " " or Mn " ", p = 1). As indicated, only monomeric hydrolysis species have been accepted for both manganese(II) and manganese(III). Although polymeric species have been postulated for manganese(II) (Fontana and Brito, 1968), these stability constant data are not retained due to the lack of confirmatory evidence. 

Stability constant data have been determined for the monomeric manganese(II) hydrolysis species, MnOH to Mn(OH)4 , from the vicinity of room temperature (15-25°C) to 300"C (Perrin, 1962a Macdonald, 1976 Bottcher and Usdowski, 1990). These data, together with a small amount of other accepted data, are listed in Table 11.20. Fontana and Brito (1968) also studied the hydrolysis of the manganese(II) ion at 25 "C and in 1.0 mol 1 NajSO. For the MnOH" " species, they postulated a stabihty that was consistent with available data from studies using other media. They also postulated the formation of the two dimeric species, Mn20H " and Mn2(OH)3. There is no confirmatory evidence for either of these species and, as such, the data for them are not retained. 

The results of potentiometric titration, the number of edge sites, and intrinsic stability constants of the protonation and deprotonation reactions of calcium-, copper-, zinc-, manganese(II)-montmorillonites, and KSF montmorillonite are shown in Table 2.4. As a comparison, some similar data for other montmoril-lonites are also listed. 

Table 11.23 Data for the stability constant of the first monomeric species of manganese(lll), MnOH (reaction (2.5), M = Mn, p= q = 1).

Example A8.1. Stability Relations of Iron and Manganese Compounds at pH = 7 Discuss the stability relations of Fe and Mn compounds with the help of activity ratio diagrams for the conditions pH = 7, HCO3" = 10 M, and S04 = 10" M. The equilibrium constants at 25°C can be obtained from the data on the free energy of formation in Appendix C at the end of the book. 

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