Aquation

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

Solvation of iron and chromium complexes in alcohol–water mixtures

Abstract: Solubilities are reported for the perchlorates of five iron(II)-diimine complexes in t-BuOH–H2O and one in MeOH–H2O mixtures, for three iron(III)-3-hydroxy-4-pyranonate and three iron(III)-3-hydroxy-4-pyridinonate complexes in MeOH–H2O and t-BuOH–H2O, and for two chromium(III)-3-hydroxy-4-pyranonate complexes in MeOH–H2O. Transfer chemical potentials are thence derived for the various iron(II), iron(III) and chromium(III) complexes, for transfer from H2O into the respective mixed solvents (at 298.2 K). These results are combined with values reported earlier for related complexes, and for other alcohol–H2O mixtures, to give an overall picture of solvation, expressed in the thermodynamic format of transfer chemical potentials, for iron(II)-diimine, iron(III)-3-hydroxy-4-pyridinonate and chromium(III)-3-hydroxy-4-pyranonate complexes in H2O-rich aqueous-alcohol mixtures. Some spectroscopic (1H-n.m.r.; i.r.) and kinetic (aquation rate constants at 298.2 K) data are reported for the chromium(III) complexes.

Kinetic studies on spontaneous ligand substitution in [Cr(S-pdtra)(H2O)]–NCS– and [Cr(edtrp)(H2O)]–NCS– systems

Abstract: The kinetics of anation of [Cr(S-pdtra)(H2O)] and [Cr(edtrp)(H2O)] complexes (S-pdtra=S-propane-1,2-diamine-N,N,N′ -triacetate, edtrp=ethylenediamine-N, N,N′-tripropionate) by thiocyanates and aquation of the [Cr(NCS)(S-pdtra)]– and [Cr(NCS)(edtrp)]– ions have been studied in aqueous HClO4 solutions. The rate laws and the activation parameters have been determined and discussed. The observed decrease in reactivity for the edtrp complexes corresponds with a changeover of the reaction mechanism from Ia to Id for reactions of the CrIII-S-pdtra and CrIII-edtrp species, respectively.

Multinuclear magnetic resonance studies of the aqueous products of the complexes cis- and trans-Pt(amine)2(NO3)2

Abstract: The hydrolyis or the aquation reactions of the compounds cis- and trans-Pt(amine)2(NO3)2 were studied in D2O in different conditions of pH. The products were characterized by multinuclear (195Pt, 13C, and 1H) magnetic resonance spectroscopy. In acidic medium, the product was [Pt(amine)2(D2O2)]2+ and for a few amines, trans- [Pt(amine)2(D2O)(NO3)]+ was detected. The 195Pt NMR resonances of the diaqua complexes were observed at higher fields for the cis compounds (avg. –1727 ppm) than for the trans isomers (avg. –1560 ppm). At basic pH, Pt(amine)2(OD)2 was formed and for ethylamine, trans-Pt(EtNH2)2(OD)(NO3) was detected. The cis compounds were also observed at higher fields than the trans isomers (–1706 ppm vs. –1574 ppm). The coupling constants with 195Pt were geometry dependent. The avg. 2J(195Pt-1H) values for the diaqua species were 66 (cis) and 57 (trans) Hz, while the avg. 3J(195Pt-1H) were 43 (cis) and 34 (trans) Hz for the diaqua compounds, and 43 and 37 Hz, respectively, for the dihydroxo species....

THE CONVERSION OF Rh(m) CHLOROCOMPLEXES TO BROMOCOMPLEXES AND THEIR SOLVENT EXTRACTION BEHAVIOUR

Abstract: This paper details investigations on the conversion of Rh(HI) chlorocomplexes to bromocomplexes, followed by the extraction of the tatter with an alkylated 8-hydroxyquinoline and their subsequent stripping with hydrobromic acid. It was found that in contrast to Rh(III) chlorocomplexes, the analogous bromocomplexes underwent significantly less aquation, thus rendering themselves to qualitative solvent extraction. Of the extractants tested, Kelex 100 proved to give the best performance. On the other hand, stripping was problematic. It was apparent that complex transformation of the extracted Rh(HI) occurred in the organic phase upon aging, which resulted in metal lock up.

Conductance of some cobalt(III) complexes in water at 25°C. Part 1.—Conductance of salts of trans- and cis-dinitrobis(ethylenediamine)cobalt(III)

Abstract: Precise conductivity results are reported for aqueous solutions of seven salts of trans- and cis-[Co(en)2(NO2)2]+. They are analysed in terms of the full Pitts equation and the association constants for the salts, although small, are found to increase with increasing radii of the ions, being particularly large for cis-[Co(en)2(NO2)2]I. Contrary to popular belief, trans-[Co(en)2(NO2)2]ClO4 is also appreciably associated in dilute aqueous solution. Rate constants for the very slow aquation of these cations are also reported.