Kinetics of the 1 : 1 complexing of oxalate to hexa-aquamolybdenum(III)
| Autor: | David T. Richens, Helen M. Kelly, A. Geoffrey Sykes |
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| Rok vydání: | 1984 |
| Předmět: | |
| Zdroj: | Journal of the Chemical Society, Dalton Transactions. :1229 |
| ISSN: | 1364-5447 0300-9246 |
| Popis: | The kinetics of the 1 :1 equilibration of oxalate with [Mo(H2O)6]3+ have been investigated spectrophotometrically at 350 nm in aqueous p-toluenesulphonic acid (Hpts) at 25 °C, I= 1.0 M [Li(pts)]. For the range of [H+] values studied, 0.35–0.90 M, protonated forms of oxalate are present. The [H+] dependence, equation (i), is consistent with HC2O4– and not H2C2O4(acid dissociation keq=k1Ka[Mo3+]//[H+]+Ka+k–1[H+](i) constant Ka= 0.084 M at 25 °C) as the dominant reactant, where k1 and k–1 are as defined in equation (ii). At 25 °C, k1= 0.49 ± 0.1 M–1 s–1 and k–1=(4.2 ± 0.2)× 10–4 M–1 s–1, giving an Mo3+ HC2O4– [graphic omitted] Mo(C2O4)++ H+(ii) equilibrium constant of 1 170 ± 100, which is in agreement with an independently determined value of 1 230 ± 460. Using trifluoromethanesulphonic acid instead of Hpts, k1 is 15% higher but k–1 remains unchanged. The results are discussed in terms of a model in which the oxalate chelates to the metal. |
| Databáze: | OpenAIRE |
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