Aquation

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

Kinetics of reactions of Schiff-base complexes of iron(II). Part IV. Reaction of tris-[α-(2-pyridyl)benzylideneaniline]iron(II) complexes with cyanide in aqueous alcohols

Abstract: Kinetics of reaction of tris-[α-(2-pyridyl)benzylideneaniline]iron(II) complexes with cyanide in a range of aqueous alcohols indicate a bimolecular reaction mechanism. Second-order rate constants correlate with rate constants for aquation of the respective complexes, and with Grunwald–Winstein solvent Y values.

Photochemistry of (.mu.-oxo)bis(pentaammineruthenium(III))

Abstract: Irradiation of the title complex in aqueous solution at pH 10 leaves the ..mu..-oxo bridge of the dimer intact and results in substitution of one ammonia by water. The quantum yield is 4 x 10/sup -3/ for irradiation wavelengths of less than 500 nm. The photoproduct decomposes to monomeric Ru(III) complexes at a rate of 1.9 x 10/sup -3/ s/sup -1/ at 0/sup 0/C; the activation energy for this process is about 10 kcal mol/sup -1/. Similar substitutional photochemistry is observed in acetonitrile, but irradiation of the complex in liquid ammonia solution leads to no new products. The nature of the photoactive state is considered. 26 references, 8 figures, 3 tables.

Kinetic studies on H+-catalyzed aquation and hydrogen peroxide oxidation of tris-asparaginatochromium(III)

Abstract: Tris-asparaginatochromium(III), [Cr(Asn)3]0 (where Asn forms a 5-membered chelate ring via amine nitrogen and α-carboxylate oxygen atoms) and its mono- and diaqua-derivatives were obtained, and their acid-catalyzed aquation was studied. The first reaction for [Cr(Asn)3]0 and [Cr(Asn)2(H2O)2]+ is the chelate ring opening at the Cr-NH2 bond, leading to metastable intermediates. Kinetics of these processes were studied spectrophotometrically in 0.1–1.0 M HClO4 at 303 and 333 K, respectively. A linear dependence of kobs on [H+], kobs = a + b[H+] was determined for both the complexes. Additionally, oxidation of chromium(III) to chromate(VI) by hydrogen peroxide was studied. The process proceeds through a chromium(V) intermediate, which is next transformed, in faster parallel steps into CrO42− and [Cr(O2)2]3− anions. The latter species, a chromium(V)-peroxo complex, is metastable under a large excess of H2O2. Kinetics of oxidation of [Cr(Asn)3]0 were studied at 298 K, at constant [OH−], within 0.2–1.0 M H2O2 range. A linear dependence of kobs on H2O2 was established. A mechanism is proposed, where the rate-determining step is an inner sphere 2-electron transfer within a precursor chromium(III) complex with coordinated O2H− anion of the [Cr(Asn)2(OH)(HO2)]− formula. EPR results provided clear evidence for formation of a relatively stable tetrakis(η2-peroxo)chromate(V) complex, [Cr(O2)4]3−.