fluorescence
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Ruthenium - A strange element
I got a small amount of RuCl3 from a friend a while ago. He purchased this from a big chemical supplier and I took a sample when we opened
the bottle for the first time. So I can be sure the Ru is real.
Since then I've been running all sorts of experiments for youtube but none of them would work. This included trying to reduce it to Ru(II) with any
possible reducing agent I could think off, from molten Sodium, to Borohydride, Aluminiumhydride, reduction with Mg or Al in acid under inert
atmosphere...it would discolor a bit and I guess the dilution turns the expected blue color into something rather grey but I couldn't do anything
useful with it yet, either.
- It won't color with Thiocyanate (red -> blue)
- It won't react with Thiourea
I just can't find anything that will visibly change that brown solution. And this is also where it starts. If you start of with RuCl3 and
you add it to water there chloro-ligands are bonded quite tighly to the Ru(III), according to literature no chloride can be precipitated from it. This
will then start to exchange ligands till a [Ru(H2O)6]3+ forms (not this one doesn't deprotonate that readily in water
like Fe(III) does.
The different Chloro-Aqua-phases can have cis/trans isomerism which are two different colors and this can be influenced by the conc. of the HCl you
add to it.
And guess what didn't work....yep even preparing the solution. Ru(II) for example can coordinate (if present as Amine complex) to almost anything even
molecular Nitrogen to form Ru-N2 complexes but I'm far from that step yet. I guess this element has a really beautiful colorful chemistry
but at the moment, no matter what I try I only end up with a brown solution (RuCl3) and that's all.
So I did another test on it today and tried to make the colorless compound [Ru(CN)6]4- because I thought a discoloration might
be at least some reaction you can see.
So as literature suggests I added a huge excess (just to make sure this time) of KCN to a very dilute RuCl3 solution and boiled it for 5
minutes....it turned dark...great. So I diluted it to yield this beautiful blue-purple (it was more of a purple) color.
I looked in every Ruthenium book I have and there is a Ruthenium purple but this compound contains Iron...which my sample definitely doesn't have. So
I looked further and found an old report on it:
http://onlinelibrary.wiley.com/doi/10.1002/zaac.19281730107/...
The author claims to have made a blue Ru[Ru(CN)5(H2O)]. So a mixed composition of Ru(II) and Ru(III) and this might even make
sense. Somehow my Ru(III) has to be reduced to Ru(II) anyways. I mean for this [Ru(CN)6]4- you can take Ru(III), Ru(IV), some
even say higher Ruthenium compounds and boil it in cyanide and it will yield Ru(II) always...so maybe the [Ru(CN)6]4- really
formed and unreduced Ru(III) formed a complex with it similar to prussian blue....
So what I did was now to test the pH of my RuCl3 solution. You know I used a solution I prepared a couple of weeks ago because I hoped for
the ligands to exchange. If the Cl is stronger bonded I'd like to start off with something more reactive. And it turns out the pH was at 4. Now this
is either Ru somehow acting as cationic acid...which I can't really believe or maybe the water I used to make it contained some acid (which also seems
highly unlikely).
So the next step was now to heat freshly dissolved RuCl3 again with an insane amount of KCN (because, as James Veitch once said it in his
TED talk, 'you have to be consistent'  ) and heated it again to boiling
temperatures. What came out was a brown solution again...yay....so I added some HCl to it... to my surprise no cloud of HCN formed so maybe it was
already coordinating to the Ru and heated it again...this time it turned colorless...colorless like the [Ru(CN)6]4- is supposed
to be (and of course I didn't have my camera running for youtube for the first experiment that actually worked  ). Then I took some of the cooled colorless [Ru(CN)6]4- and added it to a fresh solution of
RuCl3 and it turned slightly greenish...which is why I have descided to stop it for today....
It appears like the chemistry of a fresh solution and an old solution of RuCl3 seems to be different.
If anyone has any suggestions to what acutally happens here I'd be super happy for anything here .
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fluorescence
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A little update on this. So I examined the green mixture from yesterday and it turned blue. I have a bunch of tubes and flasks standing around now but
only one of them, where the coloress (today turned slightly yellow due to oxidation) Cyanoruthenate(II) was mixed with cold RuCl3 solution. So it
really appears to be a similar compound like prussian blue, a Ruthenium(III)-Cyanoruthenate(II) which I cannot find like this in literature besides
the blue compound I mentioned yerstay which is by today heavily discussed about whether it really exists....but I guess I just made it .
Also I repeated the Thiocyanate experiment and it worked once I boiled it. I tried the Cyanoruthenate(II) again as well and it would onyl decolorize
as I added a bit of acid. So I believe when you start from a nearly anhydrous RuCl3 like me you have to either heat it or change the pH value a bit as
the Ru-Cl bond is reported to be quite strong and only really slowely breaks in water...
When I'm back at University on monday I will have a look at the Gmelin on Ruthenium.
[Edited on 10-3-2017 by fluorescence]
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tsathoggua1
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Given your starting with a chloride of ruthenium, would it not be possible to react with silver compounds in a metathesis reaction to give the
ruthenium salt containing whatever counterion was bonded to Ag and precipitate insoluble AgCl, in a manner similar to argentometry, only, using it
more for transfer of ligands to ruthenium?
Perhaps reaction with an organosilver compound and pyrolysis under inert gas (argon, be aware that silver forms an extremely sensitive primary
explosive nitride) may give metallic ruthenium. Or you could use some for electroplating, could make for use in catalysts plated onto various
substrates, although I am not familiar with specificity of its preferred substrates and selectivity.
[Edited on 12-3-2017 by tsathoggua1]
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fluorescence
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The idea is good but there are several problems:
Ruthenium chemistry is somewhat special and it's of course the internet and common literature, again that don't show the true side of this element.
I'm a hardcore inorganic chemist but I have to salute organic chemistry for how much work they put into a single element. For many of the transition
metals I'd say based on the things I used them for and what I read about many of them each has a totally different chemistry to begin with.
For Ruthenium it's the fact that you cannot buy RuCl3. You can't even really make it. You have to imagine even if you took ultrapure Ruthenium and
reacted it with Chlorine in an ultravacuum you would still have oxygen contamination, Yttrium-Fluoride-systems are pretty much the same. Commercial
RuCl3 however is made from the Tetroxide...yeah you take RuO4 and add HCl to it and hope that there is also a ligand exchange involved ( I know
Wikipedia says they make it from the elements but often the commercial form from higher oxides and HCl). And even if they use the other method they do
this quite poor. Analyses show that the biggest part of commercial RuCl3 is in fact something like Ru(OH)Cl3 making the oxidation state something
close to +4. The aqueous solution of this often contains Di- and polynuclear, oxygen or hydroxy or aqua bridged complexes. So a different aqueous
chemistry.
If you took the really pure RuCl3 and added it to water it would go through several ligand exchanges. It is said (I didn't test it yet) that dry and
pure RuCl3 will not precipiate Chloride with Silver in water. If you wait a little while however it will start to exchange. And I already showed that
heated, acidified and older solutions behave completely different...
So I could try that probably but I don't even know what might form then. And experiments show that for example carbonates produce different compounds
than chlorides in reactions so this is a totally messed up chemistry. There is a good book on it, 1300+ pages only dedicated to this stuff and I try
to reproduce as much of it as possbile but at the moment I'm more fighting with trying to repoduce the same colors as they did back then when they
characterised it.
I'm happy to start with the chloride as this is often used. Bromide for example will show copletely different complexes and colors and I cannot
characterize them in my home lab, I can only reproduce and once I get the same colors I can post it on youtube.
But thank you for the suggestion, I will surely try it, soon just to see what happens.
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Melgar
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Hey, I'll have you know, organic chemistry uses at least SIX elements: hydrogen, carbon, oxygen, nitrogen, sulfur, and phosphorus, not to mention
organohalides, all the organometallic compounds and all the inorganic catalysts. We're not just playing with pure graphite here. 
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