Aquation

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

The Reaction of the Aquopentamminechromium(III) Complex Ion in Aqueous Solution. I. Substitution Reaction of a Coordinated Water with a Chloride Ion

Abstract: The substitution reaction of aquopentamminechromium(III) ion in which a coordinated water molecule is replaced by a chloride ion was investigated spectrophotometrically. The reaction proceeds according to the second order rate law, d[[Cr(NH3)5Cl]2+]/dt=\overrightarrowk2[[Cr(NH3)5OH2]3+]. [Cl−], and the rate constant varies regularly with the ionic strength of solution according to the Debye-Huckel type equation. The formation of outer sphere association complex in the solution was detected from the change in ultraviolet absorption. From these results the ratedetermining process of this reaction was inferred to be a unimolecular process through the outer sphere association complex. The experimental activation energy and the frequency factor of this reaction were determined to be 24.6 kcal.mol−1 and 1.2×1014l. mol−1min−1 (ω∼0.52), respectively.The aquation of chloropentamminechromium(III) ion was also studied in the solutions of various ionic strengths and the reaction rate was found to vary to some extent ...

Photochemical behaviour of Tc2OCl104– and TcnOy4n–2y+ in chloride media

Abstract: The stabilities of the technetium polymers: Tc 2 OCl 10 4- and Tc n O y 4n-2y+ have been studied under light irradiation in 3 M chloride media with a pH range from 0 to 1.3. It has been shown that under irradiation, Tc 2 OCl 10 4- is not stable and undergoes dissociation to TcCl 5 (H 2 O) - at pH = 0 and pH = 0.3. At pH = 1, irradiation of Tc 2 OCl 10 4- leads to a stationary state involving TcCl 5 (H 2 O) - and Tc 2 OCl 10 4- . At pH = 1.3, Tc n O y 4n-2y+ remains stable under irradiation. Under light irradiation, the predominance diagram of Tc(IV) species obtained from Tc 3 OCl 10 4- aquation in a pH range from 0 to 1 is drawn. The chemical behaviour of Tc 2 OCl 10 4- and the influence of the light on the condensation of Tc(IV) and solubility of TcO 2 ·xH 2 O are discussed.

Effects of electrolytic dissociation upon rates of reactions. Part 11. Metal ion catalysed rates of aquation of penta-ammineoxalatocobalt(III)

Abstract: Association constants (KML) of ion pairs formed between a series of divalent metal ions [including magnesium, and also lanthanum(III) ions](Mn+) and the divalent anion (L2–) of the complex penta-ammineoxalatocobalt(III) have been calculated from spectrophotometric u.v. absorbance measurements under virtually static conditions at 50 and 60 °C with ionic strength I= 0.5 mol dm–3. Some of these constants have also been estimated from e.m.f. measurements of a glass electrode/calomel electrode cell under the same conditions. Rate coefficients of aquation (kobs.) of the cobalt(III) species in the metal salt solutions at 60 °C and I= 0.5 mol dm–3 were determined from timed u.v. absorbance changes. From the kobs. and KML data, rate coefficients (k3) of the metal-oxalato ion pairs were estimated. The figures for the transition metals of the first series (manganese, cobalt, nickel, copper, and zinc) and for magnesium indicate an approximate linear relationship between the KML and k3 values; in terms of this, the k3 values for cadmium, lead, and lanthanum are of a lower order. There is a broad similarity between these features and those reported by others for various metal ion catalysed reactions, such as the rates of decarboxylation of 3-oxoglutaric acid.