Aquation

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

Radiolysis of aqueous solutions of ruthenium(iii) hexa-ammine chloropenta- ammine.

Abstract: Ru(NH3)63+ is reduced by e–aq and by the radical CH2OH to Ru(NH3)62+. Similar reduction of Ru(NH3)5Cl2+ first gives Ru(NH3)5Cl+ which aquates to Ru(NH3)5H2O2+ with a rate constant 4·7 sec.–1. The aquo-ion reduces the original Ru(NH3)5Cl2+ to give Ru(NH3)5Cl+ and Ru(NH3)5H2O3+ with a rate constant 1·0 × 103 l.mole–1 sec.–1, so that the aquation of Ru(NH3)5Cl2+ is catalysed by small amounts of the reduced species.Oxidation of Ru(NH3)63+ by OH appears to give Ru(NH3)64+ as the primary product, which decays by a bimolecular process (k= 4·5 × 109 l. mole–1 sec.–1) to give species tentatively designated as Ru(NH3)65+ and Ru(NH3)63–. The former has a half-life of 0·75 sec. and leads to products which decay slowly during hours. Oxidation of Ru(NH3)5Cl2+ differs in that there are three compounds formed successively in first-order processes after the primary oxidation step, with rate constants 2·5 × 105, 44, and 0·45 sec.–1. It is suggested that these are aquation products formed from Ru(NH3)5Cl3+.Absorption spectra of the intermediates have been obtained.

Optically active co-ordination compounds. Part XXX. Mono-dipeptide complexes of cobalt(III)

Abstract: Chloride and perchlorate salts of the cations [Co(NH3)3(α1α2)]+ and [Co(dien)(α1α2)]+, where α1α2H2 is a dipeptide, and dien = diethylenetriamine, have been prepared and characterised. A general structure for these complexes is proposed, in which the dipeptide ligand is terdentate and planar, having lost the amide proton. The protonation of [Co(dien)(glygly)]+ and [Co(NH3)3(glygly)]+ has been studied in detail by electronic absorption and 1H n.m.r. spectroscopy; complexes in which the oxygen atom of the amide group is protonated have been isolated from solutions in concentrated perchloric acid. In hot concentrated hydrochloric or hydrobromic acid [Co(NH3)3(glygly)] ClO4 gives crystalline [Co(NH3)3(glyglyH2)X]X2(X = halide) containing a bidentate peptide ligand. Concentrated aqueous solutions of this product deposit crystalline [Co(NH3)3(glyglyH)X]X, in which the peptide remains bidentate. Dilute aqueous solutions of [Co(NH3)3(glyglyH2)Cl] Cl2 undergo aquation as well as deprotonation; on the addition of base ring closure occurs to give [Co(NH3)3(glygly)]+. [Co(NH3)3(glygly)]-ClO4 can be recovered from dilute aqueous solutions of [Co(NH3)3(glyglyH2)Cl]Cl2 after ageing and addition of sodium perchlorate. The disproportionation of [Co(dien)(α1α2)]+ and [Co(NH3)3(α1α2)]+ in alkaline solution and the base-catalysed exchange at the methylene group of the C-terminal amino-acid are reported, together with some preliminary observations on the activation of the peptide towards condensation with aldehydes at the C-terminal residue.

Polarographic Study of Metal Complexes. VIII. Dicyanobis-(ethylenediamine) cobalt(III) Complex with a cis-Configuration

Abstract: In an aqueous solution containing an excess of ethylenediamine, i. e., under the conditions where the aquation is prevented, the dicyano-cobalt(III) complex, cis-[Co(CN)2en2]NO3, has been found to be reduced in three steps at the dropping mercury electrode (DME). The first step, corresponding to the acceptance of one electron, represents the reduction from the cobalt(III) to the cobalt(II) state, while the second and the third step were interpreted as being due to the reduction of two kinds of the cobalt(II) species formed by the overall rearrangement of ligands in solution. One such kind of cobalt species is the binuclear tetracyanocobaltate(II) complex, [Co(CN)4-en-Co(CN)4]4−, which is reduced to the metal through the cobaltate(I) complex, while the other is the cobalt(II) complexes with ethylenediamines in an equilibrium state, which are reduced directly to the metal at the DME. Namely, the second step represents the reduction from the cobalt(II) complex of the former to the cobalt(I) state, while the ...