Fluoride, formation constants with

The titration of AF+ with E in a water-acetonitrile mixture is followed potentiometrically using a fluoride ion-selective electrode. The cumulative formation constant for AlEs is determined from the titration curve. 

Fig. 8. Correlation between Pearson s hardness parameter (7P) derived from gas-phase enthalpies of formation of halide compounds of Lewis acids (19), and the hardness parameter in aqueous solution (/A), derived from formation constants of fluoride and hydroxide complexes in aqueous solution (17). The Lewis acids are segregated by charge into separate correlations for monopositive ( ), dipositive (O), and tripositive ( ) cations, with a single tetrapositive ion (Zr4+, ). The /P value for Tl3+ was not reported, but the point is included in parentheses to show the relative ionicity of Tl(III) to ligand bonds. 

A-methylimidazole with the corresponding protoporphyrin IX and protoporphyrin IX dimethyl ester complexes of chloroiron(III) and for the reaction of imidazole (Him) with TPPFeF and (PPDME)FeF. In the latter case, the first intermediate to form is, as before (equation 40), the six-coordinate high-spin PFe(HIm)F, and the second is PFe(HIm)F Him in which an external imidazole is hydrogen bonded to the fluoride. It has also been shown that reaction of hindered imidazoles such as 2-MeImH and 1,2-Me2lm with TPPFeCl introduces a steric strain with the porphyrin ring that causes about a factor of ten decrease in the formation constant, K (equation 40), and a factor of ten or more increase in the rate of chloride ion dissociation (equation 41). ... 

The effects of various fluoride complexing metal ions at 25°C can be roughly estimated from their complex formation constants (15) assuming, as has been concluded (17), that at any given acidity the Pu(>2 dissolution rate is first order with respect to free... 

Fluoride (MA-F-AS321-03-FLUORU) The concentration of fluoride is measured using a fluoride selective ion electrode. The addition of a buffer provides a high constant ionic strength, complexes iron and aluminium and adjusts the pH to reduce HFHF2 formation. Matrix effects are minimized by using standard addition. Fluoride (2003.03) - the concentration of fluoride is measured with the use of a fluoride selective ion electrode. 

Formation constants for silver(I)-olefin complexes have been obtained in aqueous solution by potentiometric methods by Hartley and Venanzi 45>. The ligands allylammonium perchlorate, but-2-enyl ammonium perchlorate, allyl alcohol and but-2-en-l-ol, were shown to have affinities for silver(I) comparable with acetate and fluoride ions the complexes are much weaker than the corresponding platinum(II) complexes, possibly due to the non-directional characteristic of the silver component of the a-bond (5s-orbital). The small difference between the formation constants for the allylammonium and but-2-enylammonium complexes and the larger difference between the alcohol complexes was assumed to be an enthalpy effect, arising from an electrostatic repulsion in the case of the unsaturated ammonium cations. 

The complexing of zirconium and hafnium ions by fluoride ions is quite extensive compared to chloro complexing, while complex ion formation w ith bromide and iodide ions is negligible. Formation constants for fluoride complexing with zirconium(IV) and hafnium(IV) calculated from the data of Connick (126), Buslaev (94), and Hume (574), have been summarized graphically by Goldstein (213). Slightly different values have been published by Bukhsh (92). Noren (15a, 401-403) has redetermined the equilibrium constants for the reaction. 

Both nitrosylation with NO and oxidation with dioxygen proceed via substitution of the labile water molecule in [Fe (edta) (H20)]. Due to the large formation constant of (2.1 0.5)x 10 M for the [Fe (edta)(NO )] species, the equilibrium with NO shown in Scheme 5 lies entirely on the product site. The connected equilibrimn with F is therefore shifted to the aqua side. In contrast to the binding of O2 to the [Fe (edta)(H20)] species, which is less favored compared to NO, the equilibrium with F lies more on the fluoride side (see Scheme 5). 

With reference to (Strub et al. 2000, 2001), Toyoshima et al. (2008) have re-examined the fluoride complexation of Rf in mixed HF/HNO3 solutions by determining %ads values for Rf and correlating them with the relationship between and %ads for Zr and Hf as in (Haba et al. 2004). The variation of the values of Zr and Hf under static conditions and values of Rf from column chromatography as a function of the equilibrated concentration of free ([F ]eq) is shown in O Fig. 20.21a. The solid, dashed, and dotted curves are results of theoretical calculations by Haba et al. in which the log is related to the formation constants... 

Nearly all of the formation constants listed in Table 8.8 are for complexes formed by Am(iii), as little work has been done on complexes of americium with oxidation states higher than iii. Color changes indicate existence of Am(vi) nitrate, sulfate, and fluoride complexes. There is also spectrophotometric evidence [299] for the existence in 1 m NaOH solution of a peroxide complex of... 

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