Aquation

About: Aquation is a research topic. Over the lifetime, 1443 publications have been published within this topic receiving 17507 citations.

Hydroxide ion assisted aquation of tris(2,2'-bipyridine)chromium(III) ion

Abstract: E,, kcal/mol 22.9 i 0.2 21.3 i 0.2 19.5 i 0.5 AH*296, kcal/mol 22.3 f 0.2 20.7 I: 0.2 18.9 i 0.5 InA 26.1 i. 0.1 24.1 i 0.2 24.8 r 0.9 AG 296, kcal/mol 24.9 i. 0.3 24.5 i 0.3 22.2 i 1.1 k,,,, s-' 3.3 x 6.9 x 2.9 x

Kinetics of aquation of the complex tris[3-(2-pyridyl)-5,6-bis(4-phenylsulphonato)-1,2,4-triazine]iron(II) and its reactions with hydroxide, cyanide, and peroxodisulphate ions

Abstract: The kinetics of the reactions of the complex tris[3-(2-pyridyl)-5,6-bis(4-Phenylsulphonato)-1,2,4-triazine]iron(II) in acid soloution, and with hydroxide, cynide, and peroxodisulphate ions, and hydrogen peroxide, have been investigated. The dependence of the observed rate constants on reagent concentration has been established for the reactions in acid, and with hydroxide and peroxodisulphate ions, at 35·0 ° C. For the reaction with cyanide ions, the rate law has been established and, from measured rate constants over a range of cyanide-ion concentrations and over the temperature range 25·3–44·1 °C, activation parameters both for cyanide-ion attack and for complex dissociation have been estimated. The variation of the rate of cyanide-ion attack with solvent composition has been determined for ethanol–water mixtures containg up to 30% ethanol. Patterns of reactivity for this complex are compared with those previously established for other low-spin iron(II) chelate complexes.

Oxidation of nickel(II) ethylenediaminetetraacetate by carbonate radical

Abstract: Reactions of the carbonate radical (CO3•–), generated by photolysis or by radiolysis of a carbonate solution, with nickel(II) ethylenediaminetetraacetate [NiII(edta)]2– were studied at pH 11.4 and ionic strength (I)= 0.2 mol dm–3. Time-resolved spectroscopy and kinetics for the transients were studied using flash photolysis whereas the stable products arising from ligand degradation of the complex were ascertained by steady-state radiolysis experiments. From the kinetic data it is suggested that CO3•– reacts initially with [NiII(edta)]2– to form a five-co-ordinated NiIII species [k=(4.5 ± 0.4)× 107 dm3 mol–1 s–1] which undergoes aquation with a first-order rate constant of (1.1 ± 0.3)× 103 s–1 to give [NiIII(edta)(H2O)]–. The latter reacts with iodide with a rate constant of (5.5 ± 0.4)× 105 dm3 mol–1 s–1. At the alkaline pH used [NiIII(edta)(H2O)]– undergoes transformation to give a radical intermediate which reacts with [NiII(edta)]2– to give ligand degradation products of which glyoxylic acid and formaldehyde were detected.

Aquation of the Chloro Pentaammine Complexes of Cobalt(III) and Chromium(III): Do the Almost Equal Activation Parameters Arise from a Common Mechanism?

Abstract: The activation parameters for the aquation of Co(NH3)5Cl2+ and Cr(NH3)5Cl2+ are almost equal, and the strongly negative volumes of activation, ΔV⧧ (−9.9 and −10.6 cm3 mol-1 for Co and Cr, respectively), might at the first glance suggest a common associative mechanism for both complexes. Computations of the corresponding reaction coordinates indicate that, in agreement with Swaddle and co-workers' studies and as expected, a dissociative interchange mechanism (Id) operates for cobalt(III), but an associative interchange one (Ia) for chromium(III). For these two asymmetric reactions, the bond lengths changes δCo and δCr that are involved in the formation of the transition state and defined with respect to the fully concerted I pathway allow the attribution of the reaction mechanism. The signs of δCo and δCr, being positive and negative, suggest a d and a activation for the above aquations.