Aquation

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

Kinetics and mechanism of the aquation of a series of mixed-metal oxo-centered trinuclear cations, μ3-oxo-triaqua-hexakis(carboxylato)bis-(chromium(III)(iron(III))+, [ (RCOO)6(H2O)3]+, (R=H, CH3, CH3CH2 and (CH3)2CH) in perchloric acid media

Abstract: The aquation of a series of [Cr2Fe(µ3-O)µ2-(RCO2)6(H2O)3]+ cations, where R = H, CH3, CH3CH2, and (CH3)2CH was investigated in aqueous perchloric acid, 0.01 ≤ [H+] ≤ 0.17 mol dm−3 and 25 ≤ θ ≤ 35°C. The mechanism is postulated as an equilibrium between the protons and the complex cation, where the oxygens of the carboxylate coordinated to the metal center are protonated, followed by Fe–O bond cleavage. This is followed by rapid decomposition to produce aqueous iron(III), a dinuclear chromium(III) species (which is further hydrolyzed), and carboxylate ions. First-order rate constants for the reactions at 25°C and 0.5 mol dm−3 ionic strength (NaClO4) and corresponding activation parameters are: R = (CH3)2CH; k 1 = (7.18 ± 0.07) × 10−5 s−1 (ΔH ‡= 52 ± 2 kJ mol−1, ΔS ‡= −151 ± 8 J K−1 mol−1), R = CH3CH2; k 1 = (13.67 ± 0.02) × 10−5 s−1 (ΔH ‡= 57.8 ± 0.6 kJ mol−1, ΔS ‡= −125 ± 2 J K−1 mol−1), R = CH3; k 1 = (17.6 ± 0.3) × 10−5 s−1 (ΔH ‡= 30 ± 5 kJ mol−1, ΔS ‡= −216 ± 16 J K−1 mol−1), R = H; k 1 = (3.86 ± 3.01)...

Studies on the µ-(NN′)-ethylenediaminetetra-acetato-di-µ-oxo-bis-[oxotungstate(V)], [W2O4(edta)]2–, complex in aqueous solutions. Formation of an aquo-ion and redox properties

Abstract: The aquation of [W2O4(edta)]2–(edta = ethylenediaminetetra-acetate) to W2O42+(or a closely related species) proceeds to completion in HCl 2 mol dm–3. First-order kinetics have been observed, with the rate constant (1.16 × 10–4 s–1 at 25 °C) in 2 mol dm–3 HCl some 60 times less than for the corresponding reaction of [Mo2O4(edta)]2–. With HClO4 2 mol dm–3 aquation is accompanied by oxidation to WVI. No aquation (or oxidation) has been observed with HClO4 107 dm3 mol–1 s–1 respectively. For the [IrCl6]2– reaction activation parameters are ΔH‡= 5.4 kcal mol–1 and ΔS‡=–13.8 cal K–1 mol–1 respectively. Rate constants (dm3 mol–1 s–1) for other oxidants, I= 0.10 mol dm–3, are [Fe(CN)6]3–(0.058), [Co(bipy)3]3+(2.0)(bipy = 2,2′-bipyridine), and I3–(ca. 20). The complex [W2O4(edta)]2– is a much stronger reducing agent than [Mo2O4(edta)]2–.

Dalton communications. Effect of amine substituents and neutral leaving groups on the activation volume for aquation of octahedral pentaamine complexes of CrIII and RhIII

Abstract: The activation volumes were obtained for the aquation reactions of [M(RNH2)5L]3+(M = Cr, R = Me, L = Me2SO, HCONMe2 or MeCONMe2; M = Rh, R = H or Me, L = Me2SO or HCONMe2); they are in accord with the existence of a dissociative shift in the substitution mechanism, not only with the size of the substituent R, but also with the size of the leaving ligands L.

Aquation of tris-(1,10-phenanthroline)iron(II) complexes in aqueous ethanol and in aqueous formic acid

Abstract: Rates of aquation of tris-(1,10-phenanthroline)iron(II) complexes have been determined in series of aqueous ethanol and aqueous formic acid solvent mixtures. Variation of aquation rate with solvent composition for the 5-nitro- and 4,7-dimethyl complexes in the two series of solvents suggests that, in the favourable case of the electron-withdrawing nitro-substituent and of aqueous ethanol as solvent, bond-making between iron and incoming water is of some significance in transition-state formation. An attempt is made to extend the use of the Grunwald–Winstein concept of the relation between reactivity and solvating power of solvents to these inorganic systems.