Talk:Metal aquo complex

pK values
I've remove this column because a single figure won't do it justice. There is temperature and ionic strength to consider and there is some disagreement, cited in Baes and Mesmer, between reported values. Part of the problem is uncertainty as to hydrolysis beyond the first step. In summary, the data are not suited to be reported in a single column. Petergans (talk) 12:42, 30 March 2011 (UTC)

Error in article
The reported water exchange rate of the Cu(II)aqua complex is from Pasquarello et al. science, 2001, 291, 856. But that article claims Cu(II) to be five-coordinated in water. If sixfold-coordination is assumed, the exchange rate should be 4.4 x 10^9 s^-1. — Preceding unsigned comment added by 130.226.178.140 (talk) 16:43, 9 November 2012 (UTC)
 * So the number reported in the table is no good? Or has the analysis been revised to indicate [Cu(H2O)6]++ with the 4.4 x 109 s-1?  A citation to this correction would be very welcome.  --Smokefoot (talk) 22:10, 10 November 2012 (UTC)

The number in the table is valid if Cu2+ is five-coordinated in water. However, the coordination number of the Cu(II) aqua ion is still an open case! de Almeida et al. are in favour of a six-coordination (doi:10.1016/j.chemphys.2006.11.015), but they did not test the possibility of four-coordination! That is important because the results of O'Brien and Williams (dx.doi.org/10.1021/jp210878s) points towards four-coordination. Pasquarello et al. shows evidence for five coordination (doi: 10.1126/science.291.5505.856) and the general crowd of chemist seems to follow Åkesson et al. (doi: 10.1021/j100180a031) who claims six-coordination. This article refers to a paper by Helm and Merbach (doi:10.1021/cr030726o) and they did not decide on coordination number but published the water exchange rate for both the six- and five-coordinated Cu(II) aqua complexes and let the question be open. Before November this article showed the value of water exchange rate for the five-coordinated complex but claimed that is was for the six-coordinated complex and that is an error. Now is shows the value for the five-coordinated complex and states that it is for the five-coordinated complex. That is acceptable, but the article should state that the coordination number of the Cu(II) aqua complex is unsettled. — Preceding unsigned comment added by Dr. JaHo (talk • contribs) 20:26, 15 February 2013 (UTC)

Duplicate
Is this a duplicate of Metal ions in aqueous solution, or are these different topics? Waterfalls12 (talk) 00:55, 5 January 2015 (UTC)
 * Good point. The articles are not duplicates, but they overlap.  The two articles might be reconciled and combined, but doing so is not simply a matter of mashing the two together since they have fairly different styles. This one (Metal aquo complex) is only about transition metals and Metal ions in aqueous solution is broader, about metal ions in general.  Probably the simplest way forward would be to relabel this one transition metal aquo complexes, but that change takes involvement of an administrator and some work on repairing some links.  --Smokefoot (talk) 01:23, 5 January 2015 (UTC)
 * The section on transition metal ions in Metal ions in aqueous solution was kept deliberatly short and supplied with a shortcut to this article. I agree, it would be a slight improvement if this article were to be renamed, but it's hardly worth the candle. Petergans (talk) 07:56, 19 April 2016 (UTC)
 * This article provide no rationale or explanation for treating transition metal complexes separately. Since the other article already covers transition metals and is not excessively long, I see no reason not to merge them. 73.189.240.68 (talk) 19:33, 7 June 2017 (UTC)

"Completely off-topic"
To initiate recent deletion, which I am happy to discuss. "Completely" (really?) off topic. --Smokefoot (talk) 10:57, 30 June 2019 (UTC)
 * Metal aquo complexes are precursors to O2 in the OEC. That seems to be a topical and important reaction.
 * Most metal aquo complexes are heteroleptic. So why not mention them, such as [Ni(tach)(H2O)3]2+?  That statement acknowledges a large class of complexes.
 * [Ni(tach)(H2O)3]2+ is a complex of Ni with the tridentate ligand TACH and 3 water molecules. It's obviously an interesting species. It is off-topic in this article and the section contents could be placed in homogeneous water oxidation catalysis if it's deemed to be important enough.
 * I agree that complexes in which some water molecules are replaced by other ligands form an important group of compounds. I would class them as mixed-ligand complexes and my preference would be to include them where other complexes of the metal are discussed. Petergans (talk) 19:36, 30 June 2019 (UTC)

Water exchange and residence time
I see that the article mentions the water exchange and electron exchange aspects. I'd say that more details be added, possibly from a source that appears to contain such info like:


 * H. L. Friedman, F. Franks, Aqueous Simple Electrolytes Solutions

Any thoughts?--109.166.139.84 (talk) 00:43, 25 October 2019 (UTC)