Number 9
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stoichiometric coefficients of Cu(II)salicylate
How many salicylate ligands are there in Cu(II)salicylate? I would like to prepare such a complex for the determination of salicylic acid in aspirin.
According to wikipedia it is Cu2(C6H5OCOO)2 but they don't have any sources in their article.
Is there more information about this subject?
What colour does it have. According to my teacher it has no colour, but I'am sceptic.
Some sources claim that it has a green colour and becomes ochre after a while. (Chemical Communications, 1967, p.1057b-1058, issue 20, 1967. But
there is also one patent who claimes that it forms a blue complex. So, what article is right?
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ScienceSquirrel
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This guy has made a mistake in so far as he used copper II chloride instead of copper I chloride but he seems to have made the stuff and got all three
colours.
http://www.skylighter.com/fireworks/How-to-make-sky-rockets/...
[Edited on 28-5-2012 by ScienceSquirrel]
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Number 9
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What's the scientific explanation that there are 3 different colours for this particular complex.
Let's try it: if you mix ochre-yellow with bleu, the result will be a green complex (but it is actually not a green compound)... I predict that this
compound have 2 different absorbance peaks when you put it into the spectrophotometer.
Not the complementary colour of green (which is red), but instead of that it absorbs the complementary colour of ochre which is bleu, and also the
complementary colour of bleu, which is ochre.
But this is just a prediction and I don't have the absorbtion spectrum of Na-salicylate. Any comments?
Does anyone have a scientific paper about this subject, because this is not a good reference for university-level studies.
Another critical mistake in this article that the publisher has no name, no sources, no analytical data, no SI-units and no pictures. it's weird.
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Nicodem
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I suggest you try performing a literature search on your own. It will help you much more than waiting for others to do so, as you will learn new
skills in the process. We have The literature searching guidelines for such opportunities. It is always a better option to do the literature work first by yourself rather than
relying on others from the beginning. You can't really trust others to do an equally thorough job when not equally motivated as you are. However,
sometimes others will find references you somehow missed, so it is always a good idea to come back to present the references you already collected in
order for others to complete them with the missing ones.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Number 9
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You can't measure Copper(II)salicylate in the visible spectrum. The extinction peak starts at more then 800 nm. Also, the problem of Cu(II)salicylate
is that it forms a green slurry rapidly, and then you can't determine it with a spectrophotometer. Upon dilution, the absorbance peak is out of range.
(>800nm)
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Number 9
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Here is the picture of Cu(II)salicylate...if it really exist. Because they probably have a elektron configuration 3d104s1 at the
outer-shell when it should form a complex with a monodentate bulky ligand.
Then elektrons can not jump anymore from the teg E-level to the higer eg level. So, not sure that it really exist.
Post your comments about what causes the colour? Maybe just the CuCl2 that they used?
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Nicodem
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Who is "they"? Please do not plagiarize on this forum. Give sources for anything you cite, pictures included
| Quote: | | Here is the picture of Cu(II)salicylate...if it really exist. |
Which one? A cursory check of the literature shows several cupper(II) salicylate compounds are known. Many include additional stabilization ligands,
such as water, though plain non-stabilised copper(II) salicylate is also known.
Besides, that picture above just shows two liquids of different colour. What should we make of that? I seriously doubt that any of the copper(II)
salicylate complexes is a liquid, so utmost the picture shows a solution of some such complex, but not the complex itself, which should most likely be
a crystalline powder.
You might want to be more explicit with what exactly you want to know, if you want assistance at all. For example, in the first post you say you want
to prepare some such coordination compound, but then I wander why don't you just follow a literature procedure for its synthesis?
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Number 9
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@Nicodem, there is only a internal publication from the results. I don't give any references because op copyright protection.
What I know is that the complex is just a equilibrium and it might form several possible complexes.
You can't measure the solid ochre complex with UV-VIS, because the extinction peak lies in the IR-region. No historical data are
available on the internet.
There is a procedure but you have to pay for the article to read the full-text.
Several complexes can indeed be formed in water, but what is the stongest ligand according to the ligand-field theory. Water or salicylate?
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