Talk:Cobalt(III) chloride
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Unconvincing, crappy citations
[edit]The citations supporting this compound seem really mediocre, especially for a compound that is generally assumed to not exist. Can something better be found?--Smokefoot (talk) 18:43, 5 September 2018 (UTC)
- Obviously I am not able to evaluate the quality of the earlier references. However, I now found one from 1983 that claims observation of the compound in a frozen argon matrix, and gives the basic structure (planar, threefold symmetric). So it seems that the compound does exist. (I am at home now so I cannot get the full text of the paper, but the abstract seems categorical enough.)
On the other hand I removed the sentence
- At high enough temperature, it quickly decomposes into the cobalt(II) salt and chlorine:
- 2 CoCl
3 → 2 CoCl
2 + Cl
2
- 2 CoCl
- At high enough temperature, it quickly decomposes into the cobalt(II) salt and chlorine:
- since I could not find the reference where I got that information from.
--Jorge Stolfi (talk) 04:25, 6 September 2018 (UTC)- The article verges on OR. The sources are in weak journals and many are old. No crystal structure. The existence of Coen3Cl3 has no bearing on CoCl3. A suggested compromise: insert the words like "proposed" throughout the article. That way readers can see an article on this proposed material and can appreciate that it is a proposed species. I am still unsure what is proposed in terms of structure and magnetism.--Smokefoot (talk) 13:18, 6 September 2018 (UTC)
- What do you mean by OR? (I am old, but not that old 8-)
Have you checked this article? It claims to have obtained CoCl
3 in frozen argon, in an amount sufficient to detect spectroscopically, and determined the molecular structure. That would imply that the molecule is fairly stable at those low temperatures, at least in isolation. (But they did not detect any NiCl
3; so it is not the case that any random cluster of atoms shows up in such experiments...) Do you think that the article is not reliable?
There is also this one that apparently detects CoCl
3 in the gas phase in equilibrium with CoCl
2 in an atmosphere of Cl
2. I can't really read German, but Table 3 seems to say that CoCl
3 outnumbers CoCl
2 at 918 K. Isn't that reliable enough?
And CoCl
3 got its own CAS number... doesn't that count half a point too?
So, I still think that "proposed" is too negative. It would be appropriate for compounds that have been investigated only theoretically, such as dicarbon dioxide, but have not been detected experimentally in any form.
Would "elusive" be OK?--Jorge Stolfi (talk) 22:15, 11 September 2018 (UTC)- Jorge, about this and mercurous sulfide, CAS seems to assign registry numbers to anything that is mentioned, regardless of the reality behind the claim. If CoCl3 is not sufficiently real to be mentioned in advanced textbooks, then you are claiming knowledge beyond that of some famous authors (Wiberg, Wilkinson, Shriver, Cotton). It is that claim that is potentially problematic. As an encyclopedia, Wikapedia is a place for settled knowledge, not a place to advocate for sketchy claims. But those views are my own, and I cannot impose them. With best wishes,--Smokefoot (talk) 01:14, 12 September 2018 (UTC)
- Well, I believe that "settled knowledge" does not imply "only compounds that are stable in pure form at ambient temperature". Nitrogen dioxide deserves its article, even though it cannot be obtained pure in bulk (right?). Even compounds that are totally unstable, like dicarbon dioxide, can have enough encyclopedic "knowledge" to deserve an article. (And consider that Wikipedia has articles on unicorns, bigfoot, and the flat Earth theory..)
The article is not "advocating" anything, just reporting what little has been published about the compound. From the references, it seems that CoCl
3 definitely exists in the stated conditions, and several of its properties have been measured; it does not seem to be a "chemical unicorn"...
The lack of mention in textbooks is not evidence that those reports are invalid; the conditions are sufficiently extreme to make the compound "uninteresting" for most chemists -- wouldn't you say so?
All the best, --Jorge Stolfi (talk) 06:25, 12 September 2018 (UTC)- Reliance on primary refs is risky business. The reason that the big textbooks (i.e. WP:TERTIARY) don't discuss this material very much is possibly related to the weak references - the literature is not believable (by experts) and the compound is probably not notable. In general, building an article on primary references alone is risky. Some specific tips if you are trying to learn inorganic chemistry: Co(en)3Cl3 has nothing to do with CoCl3. There are lots of cobalt trichlorides if one (mis)defines them in this way!, (ii) consider the magnetism of CoCl3.--Smokefoot (talk) 00:07, 17 September 2018 (UTC)
- Well, I believe that "settled knowledge" does not imply "only compounds that are stable in pure form at ambient temperature". Nitrogen dioxide deserves its article, even though it cannot be obtained pure in bulk (right?). Even compounds that are totally unstable, like dicarbon dioxide, can have enough encyclopedic "knowledge" to deserve an article. (And consider that Wikipedia has articles on unicorns, bigfoot, and the flat Earth theory..)
- Jorge, about this and mercurous sulfide, CAS seems to assign registry numbers to anything that is mentioned, regardless of the reality behind the claim. If CoCl3 is not sufficiently real to be mentioned in advanced textbooks, then you are claiming knowledge beyond that of some famous authors (Wiberg, Wilkinson, Shriver, Cotton). It is that claim that is potentially problematic. As an encyclopedia, Wikapedia is a place for settled knowledge, not a place to advocate for sketchy claims. But those views are my own, and I cannot impose them. With best wishes,--Smokefoot (talk) 01:14, 12 September 2018 (UTC)
- What do you mean by OR? (I am old, but not that old 8-)
- The article verges on OR. The sources are in weak journals and many are old. No crystal structure. The existence of Coen3Cl3 has no bearing on CoCl3. A suggested compromise: insert the words like "proposed" throughout the article. That way readers can see an article on this proposed material and can appreciate that it is a proposed species. I am still unsure what is proposed in terms of structure and magnetism.--Smokefoot (talk) 13:18, 6 September 2018 (UTC)