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Aquation
About: Aquation is a research topic. Over the lifetime, 1443 publications have been published within this topic receiving 17507 citations.
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13 citations
TL;DR: In this paper, the authors studied the kinetics of the aquation and formation reactions of this carbonato complex by stopping-flow spectrophotometry, and the results are compared to those of cobalt complexes previously studied and the possible mechanisms are discussed.
Abstract: The title compound has been prepared and characterized for the first time. The kinetics of the aquation and formation reactions of this carbonato complex were studied by stopped-flow spectrophotometry. The acid catalysis reactions were studied in the range of 2 > [H’] > 0.01 M and 10 < T < 25 O C at an ionic strength of 2 M (NaC10,). Only the ring-opening reaction of Cr(C0,)(0x),~is observed, k = 2.04 M-’ s-’ at 25 OC, as subsequent decarboxylation is too fast to measure even at 2 M hydrogen ion concentration. Carbon dioxide uptake by cis-diaquobis(oxalato)chromate(III) was investigated over the ranges 7.01 < pH < 9.34 and 10 < T < 25 O C at an ionic strength of 0.5 M (NaCI). The major reactant species in the pH range studied was ~ i s C r ( o x ) ~ ( O H ) ( 0 H ~ ) ~ which takes up C02 to form ~is-Cr(ox)~(HC0~)(0H~)~. Subsequently, slower ring closure of the latter species to form the carbonato chelate is observed. The results are compared to those of cobalt complexes previously studied and the possible mechanisms are discussed.
13 citations
TL;DR: In this article, the activation entropies ΔS∗) for a series of thermal or Hg2+−assisted chloride release aquation rates from chloroam(m)ine complexes are ranked, orders for the effect of the non-replaced ligands are obtained.
Abstract: If the activation entropies ΔS∗) for a series of thermal or Hg2+−assisted chloride release aquation rates from chloroam(m)ine complexes are ranked, orders for the effect of the non-replaced ligands are obtained. These orders are within reasonable expectation for the extent of interchange that takes place as the reaction proceeds.
13 citations
TL;DR: In this article, the geometry of the reactants and products was determined by molecular mechanics and the optimized structures were used to calculate by the extended Huckel method the charge distribution and relative electronic energies.
13 citations
TL;DR: In this article, the authors investigated the kinetics of solvolytic aquation of cis-(bromo)(benzimidazole)bis(ethylenediamine)cobalt(III) have been investigated at 35, 40, 45, 50.2 and 54.8 °C in aqueous methanol media.
Abstract: The kinetics of the solvolytic aquation of cis-(bromo)(benzimidazole)bis(ethylenediamine)cobalt(III) have been investigated at 35, 40, 45, 50.2 and 54.8 °C in aqueous methanol media of methanol content 0–80 wt %. The pseudo-first-order rate constant decreases with increasing methanol content. Plots of log ksaqvs. D–1s(where Ds is the dielectric constant of the solvent mixture) and log ksaqvs. the Grunwald–Winstein Y parameter or revised YCl(1-adamantyl Chloride) parameter are non-linear. The plot of log ksaqvs. the molefraction of methanol (XMeOH), which deviates from linearity at 35, 40 and 45 °C, is an excellent straight line (r= 0.998) at 50 and 54.8 °C over the entire composition range studied. It is evident that the solvation phenomenon plays dominant role and that the rate of aquation is mediated by the dual solvent vectors, the overall basicity and acidity of the solvent mixtures. At 25 °C the calculated values of the transfer free energy of the dissociative transition state, cis-{[Co(en)2(bzmH)]3+}*, relative to that of the initial state, cis-[Co(en)2(bzmH)Br]2+, for the transfer of the ions from water to the mixed solvent were positive at all solvent compositions (except 80 % MeOH), exhibiting a maximum at XMeOH= 0.46. This reflects the propensity of the said tripositive transition state and the dipositive initial state towards solvation interaction with the medium. In contrast to the activation free energy, which varies linearly with XMeOH, the plots of activation enthalpy and entropy against XMeOH exhibit maxima at XMeOH= 0.12 and 0.46 and minima at XMeOH= 0.02 and 0.25; thereafter both ΔH‡ and ΔS‡ decrease steeply to significantly low values at XMeOH= 0.69 (ΔH‡= 80.1 ± 4.3 kJ mol–1 and ΔS‡=–91 ± 13 J K–1 mol–1), manifesting the effect of solvent-shell reorganisation around the complex ion both in the initial state and in the transition state as the composition is varied.
13 citations