Mechanistic Information from Pressure Acceleration of Hydride Formation via Proton Binding to a Cobalt(I) Macrocycle
作者:Etsuko Fujita、James F. Wishart、Rudi van Eldik
DOI:10.1021/ic011109q
日期:2002.3.1
occurring via proton transfer. Whereas the corresponding volumes of activation (DeltaV) are rather small and negative for all acids (protondonors) with pK(a) values below 8.5, significantly larger negative activation volumes are found for weaker acids (pK(a) > 9.5) containing OH groups as protondonors. In the latter case, the observed DeltaV for these protonationreactions show a correlation with the reaction
esters and 4-methylbenzoate esters by HOO- have been systematically investigated in detail. When the leavinggroups of substrates are sufficiently good (aryl, 2,2,2-trifluoroethyl, and 2,2-dichloroethyl esters), alpha-effect is evident. However, this effect drastically decreases as the leavinggroup gets poorer, and is only marginal for the cleavages of 2-fluoroethyl and methyl esters. In the nucleophilic
We reported the tunable spin-crossover (SCO) behavior in a series of halogen-functionalized cobalt(II) complexes constructed by the [Co(Brphtpy)2]2+ SCO active units and various organosulfonates.
Several ligands were designed as plausible reagents for the spectrophotometric analysis of uranyl in aqueous solutions. The ligand L-3(2-) = 3,3'-(ethane-1,2-diylbis(methylazanediyl)) bis(methylene) bis(4-hydroxybenzenesulfonate) was found to fit best the requirements. The results point out that carboxylate substituents compete with the phenolate substituents as binding sites to the central uranium cation and therefore decrease the usefulness of ligands containing both carboxylate and phenolate substituents as analytical spectrophotometric reagents.