Talk:Copper monosulfide

Comment

I have added the content to this page - previously it redirected to copper(I) sulfide. That page needs to be changed to reflect that it is a good overview of the copper sulfide phases and not just about copper(I) sulfide.--Axiosaurus (talk) 11:49, 2 March 2008 (UTC)

This lemma misrepresents the NMR paper by Saito rather badly. The paper talks about two different copper atoms Cu(1) and Cu(2) but does NOT say that those two coppers are in valence states I and II respectively. In fact it makes a comparison with authentic I and II coppers in oxides and says that things are different in sulfides. The quoted theoretical paper is quite old 1978 and predates my work from the 1980's that has found wide exceptance since. I think the lemma needs to be scrapped —Preceding unsigned comment added by Jcwf (talk • contribs) 13:37, 4 August 2008 (UTC)

I don't think it needs to be deleted outright. Definitely it should be updated, and probably renamed as well (how about copper monosulfide?), but if it is still true that there exists a compound with formula CuS, it should be covered somewhere. The formulation as Cu^I₂Cu^IIS₂S is a standard textbook account--it is mentioned in Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.. Sure, it is outdated, but let's fix it by adding the latest information instead of deleting the article. Even then, it could be useful to mention the old formula for historical purposes. --Itub (talk) 14:19, 4 August 2008 (UTC)

Certainly I do not think there is any sense in which the compound CuS does not exist- a common name is copper(II) sulfide, but I would prefer copper monosulfide.

As the editor who changed this article from a general discussion of copper sulfides to one about CuS I must apologise for my oversight that when I reorganised the article I did not duplicate the information relating to CuS from what is now the copper sulfide page e.g. the sentence "CuS, for example, can be written as Cu₃(S₂)S." with appropriate refs. That oversight should be corrected and the info added back I would however formulate CuS as (if I remember the papers correctly)3Cu⁺[S₂]⁻ S²⁻ as Jcwfs paper proposes the disulfide ion on the basis of S-S bond length, to be only singly charged. My point in adding the Saito reference was to point out that in NMR terms there is a difference between the two crystallographically distinct species of copper - the citation tag should be removed if only because it could be taken as a criticism of that paper rather than my poor use of English.

I firmly believe that oxidation state formulations that essentially localise electrons in compounds that contain a degree of delocalisation are by their nature problematic. I tried to say this but I actually wrote "mixed valence", which may be better changed. As regards the calculations ref- have there been more relevant recent papers than that old 1970s article I knew about?--Axiosaurus (talk) 17:57, 4 August 2008 (UTC)

According to Folmer, CuS should be described as (Cu⁺)₃(S^2–)(S₂)^–. I'm not an expert on this topic, but I found an abstract from 1997 that proposes (Cu⁺)₂(S^2–)(Cu⁺)₂(S₃^2–).[1] What is the current expert opinion regarding this other formula? --Itub (talk) 08:45, 5 August 2008 (UTC)

I am not an expert on CuS either! I have not read this paper but from the abstract 1) it surprises me as the Xtal data is usually interpreted in terms of containing disulfide, S₂, and sulfide S. 2) it does however overcome the problem of formulating CuS with S₂⁻, a radical anion,( CuS is quoted by some web sources (can someone confirm unequivocally the magnetic moment of CuS?) as diamagnetic - which could be taken to indicate that no Cu(II) and no S₂^- were present. As regards calculations I have found this 1993 paper doi:10.1016/0038-1098(93)90689-K that agrees with Folmers formulation. Other workers also conclude that there is no Cu(II) in covellite form of CuS e.g. doi:10.1016/j.gca.2006.02.007, doi:10.1016/0022-1902(78)80152-3.

To draw a line under this I suggest we rename the compound copper monosulfide, add in refs for Cu(II) being absent and the calculations paper and report both Cu(I) formulations, with suitable caveat about about interpretation and limitations.--Axiosaurus (talk) 13:20, 6 August 2008 (UTC)

Article move

I've moved article from copper(II) sulfide to copper monosulfide. There is clearly a compound of stoichiometry CuS, which exists in nature as the mineral covellite. However, as apparent in the discussion above, it does not seem entirely clear what oxidation state or states copper adopts. The name change avoids this problem by referring only to the stoichiometry of the compound, which is well established.

Ben (talk) 16:05, 6 August 2008 (UTC)

Rewrite of structure section

I have rewritten the structure section to reflect discussion. I have NOT included a reference to the 1997 Russian paper as I have not read it and cannot see from the crystal structure how a formulation with a trisulfide unit can be justified. I have also omitted the NMR reference as it does not add to the bonding descroption and may confuse.--Axiosaurus (talk) 14:41, 8 August 2008 (UTC)

Move warring

I've restored the article to copper monosulfide and move protected for a week. User:Flushing258 has repeatedly moved the article to Copper(II) Sulfide with no discussion. Said user has been warned and the article restored to the longstanding name. Flushing258 is encouraged to discuss the situation here to develop a consensus for their preferred name. Vsmith (talk) 05:22, 14 March 2010 (UTC)

Because this article has low visibility, I started a thread on this matter here. Materialscientist (talk) 10:07, 14 March 2010 (UTC)

Confusing solubility data

The infobox states that CuS has solubility of 0.000033 g/100 mL and solubility product 1.27 x 10^-36, which obviously doesn't correspond with each other as K_so = 1.27 x 10^-36 would give a concentration of saturated solution equal to 1.13 x 10^-18 mol/l which gives around 10^-17 g/100 ml. At least one of those data must then be false. I guess it's the solubility: As this compound is almost insoluble even in non-oxidizing acids, it must have very low solubility. K_so value seems reasonable though it also should be verified. Tomzuk (talk) 18:54, 6 March 2012 (UTC)

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