Sciencemadness Discussion Board - Antimony pentafluoride

Antimony pentafluoride

itchyfruit - 29-8-2009 at 16:47

I was looking at a sealed container of SBF5 and it contained very light free flowing dark grey/black course powder(a bit like charcoal) thinking this was strange looking stuff,i looked it up and it should be a liquid.
The container's label read Antimony pentafluoride 25g
Toxic Corrosive
moisture sensitive
store under nitrogen
It also said something like 50w/t %graphite.

So my question is why does Wiki and others say it is a liquid when the container states 25g (i do realise some liquids are sold in grams) but why is it a solid or is it a gas on graphite or has it oxidised because it wasn't under nitrogen.
please help as i'm really confused

JohnWW - 29-8-2009 at 17:02

It has to be stored away from H2O, and from anything else which could either hydrolyse it to oxo compounds and HF, or with which it could form a complex anion, being a very powerful Lewis acid.

itchyfruit - 29-8-2009 at 17:07

do you think that the dark grey powder is antimony oxide then?

UnintentionalChaos - 29-8-2009 at 17:17

Quote: Originally posted by itchyfruit

do you think that the dark grey powder is antimony oxide then?

Graphite is gray. *facepalm* It's probably adsorbed onto graphite to make handling much easier.

itchyfruit - 29-8-2009 at 17:36

That makes sense, so it should still be capable of releasing fluorine (don't worry i'm not going to try it)

ammonium isocyanate - 29-8-2009 at 18:02

I do believe that pure SbF5 is a liquid at stp, but it may be that it has been absorbed into the graphite... Although I doubt that even if such a thing does happen graphite would be able to absorb its own weight in SbF5. I suppose it is possible that the liquid clings to the graphite particles.

As for the SbF5 having been oxidized, no. SbF5 doesn't get oxidized. Even by fluorine. In fact, SbF5 when combined with F2 is such a powerfully oxidizing compound that it can oxidize oxygen to oxonium fluoroantimonate.

itchyfruit - 29-8-2009 at 19:01

I was thinking it may have absorbed h2o from the air (it's not under nitrogen) it is in a well sealed container but it looks to be a fairly old sample.
Is their a chance the fluorine could have been released as HF and then the SB oxidised ?
just a wild theory really

DJF90 - 29-8-2009 at 19:21

You mean if the SbF5 can be hydrolysed to form an "oxyhalide" species?; technically an oxidation despite what ammonium isocyanate says because you are adding oxygen to the compound (this is one of the three definitions for oxidation, the other two being removal of hydrogen, and loss of an electron). If the container appears well sealed then I expect not. If the container is glass then its age is a testament against hydrolysis - the HF formed would have etched away at the glass. Chances are if moisture got in then it can continually get in, which results in continued HF production and thus continued corrosion of the glass. Personally... I think its probably well stored.

JohnWW - 29-8-2009 at 20:08

Quote: Originally posted by ammonium isocyanate

As for the SbF5 having been oxidized, no. SbF5 doesn't get oxidized. Even by fluorine. In fact, SbF5 when combined with F2 is such a powerfully oxidizing compound that it can oxidize oxygen to oxonium fluoroantimonate.

I do not think it could do that because, if it were stored under nitrogen, it would do the same thing to nitrogen. You may be confusing it with PtF6. However, just to be on the safe side, storing it under anhydrous argon would be better.

P.S. In case you were thinking of the trifluorooxonium cation, [OF3]+, rather than the dioxygenyl cation, [O2]+ (obtained by reaction of O2 with PtF6), it has been shown to be theoretically stable, but it has never been isolated, e.g. by heating O2 or OF2, F2, and SbF5 or PF5 or AsF5 or BF3, together under great pressure, at least as recently as 1999. However, [NF4]+ has long since been so obtained as such a salt. Nor does [OF3]+ seem to have been obtained (yet) by reaction of OF2 with [KrF][SbF6]; but similar reactions have been used successfully to obtain [ClF6]+ from ClF5, and also AuF5. An attempt to obtain [XeF7]+ this way from XeF6 was unsuccessful. See:
http://www.ingentaconnect.com/content/els/00221139/1999/0000... (restricted)
http://en.wikipedia.org/wiki/Trifluorooxonium
http://handle.dtic.mil/100.2/ADA408649
http://cat.inist.fr/?aModele=afficheN&cpsidt=10285487
http://pubs.acs.org/doi/abs/10.1021/ic00182a016 (restricted)
http://www1.elsevier.com/cdweb/journals/00221139/articles/99... (restricted)

[Edited on 30-8-09 by JohnWW]

itchyfruit - 30-8-2009 at 02:38

According to Wiki sb203 is a white powder so i think we can safely assume that the dark grey powder is graphite,it doesn't feel like it weighs 25g (but i can't/won't open it to get an accurate weight) although it is pretty much full (maybe the sbf5 has all been used and just the graphite remains) it is actually in a plastic container the original from aldrich it has no obvious signs of corrosion, but it feels like it could be a little brittle.
I can get a bottle of nitrogen and make a temporary nitrogen atmosphere in an old fish tank or something remove a small amount under nitrogen then place it in a fume cupboard and add a couple of ml of water to see if it reacts i suppose that would settle it once and for all!!!

Formatik - 30-8-2009 at 12:38

Just do a web search on graphite and antimony pentafluoride that'll tell you all about your intercalated SbF5.

itchyfruit - 30-8-2009 at 14:21

Thanks,i certainly didn't think of that!!! and not only does it answer my question it also shows my original guess (a gas on graphite) wasn't that far out.
The only thing is surely being on graphite would affect it's use in organic chemistry.
But what do i know

entropy51 - 30-8-2009 at 14:26

Quote: Originally posted by itchyfruit

But what do i know

Not what 50 wt % graphite means, apparently.
Any chemistry that's not on Wiki?
Any chemistry of fluorine?
I could make a list, but I'll stop there.

itchyfruit - 30-8-2009 at 17:16

But i can make a solution,well sort ov

ammonium isocyanate - 30-8-2009 at 19:45

Quote: Originally posted by JohnWW

Quote: Originally posted by ammonium isocyanate

I'm not saying SbF5 alone will oxidize oxygen. I'm saying that it promotes oxiditaion by F2 to such a degree that oxygen will be oxidized to dioxygenyl in the presence of both F2 and SbF5.

Article

Formatik - 30-8-2009 at 19:59

Now that's oxidizing power. Btw, SbF5 in a dry air doesn't absorb oxygen, it just evaporates.

Rich_Insane - 3-9-2009 at 12:46

This is like how chloroform is often sold "stabilized" to prevent phosgene from coming out.

The graphite probably acts as something to keep the SbF5 in place.

woelen - 3-9-2009 at 22:43

Itchyfruit, given your lack of knowledge/experience -- which you very clearly demonstrate in your posts -- it is best to leave that container closed for the next few months (maybe years) and first do some studies and try to get practice with other chemicals and experiments. Do not understand me wrong, it is not bad to be inexperienced, I also have been and in some subjects I still am. But it is important that you know of your limitations and right now I do not think that you can handle SbF5 in a safe way.

I do not write this in order to offend you, but I'm really concerned. SbF5 is NOT a toy and it could easily do great harm to your health, even 25 grams can do a lot of nasty things.

itchyfruit - 4-9-2009 at 06:46

Rich Insane: I think your right,i have some nitro methane(a very small amount) that has what looks like little cylindrical pellets in the bottle,presumably for the same purpose.
Woelen: You have not offended me in the slightest. Despite being a very new member here i can see that you and the likes of DJF90,Pulverone,Kmno4,etc (even Entropy51 despite his constant piss taking)clearly know what your talking about and your concern is appreciated.
But to put your mind at rest i'd like to let you know that i have no intentions of opening this container(even under nitrogen)as quite apart from the obvious health risks i would not want to lose/ruin/destroy the contents. It is for this reason(and the fact that i don't have a clue what to do with it) that i intend to sell/trade it along with about 50 or 60 other organic solvents/reagent that i have no use for,but have to buy in order to obtain the inorganic stuff that i do want.
Once again thanks for the advice and as i've said before Great site.

arsen - 10-9-2009 at 09:37

Hi,

I believe what you have in hand is SbF5, 50% on graphite support. Pure SbF5 itself is liquid at room temperature. Aldrich sells this and you can find it in their catalogue.

They use graphite as support for better handling.

The worse thing that could happen to it if it's exposed to air is that SbF5 would get hydrolyzed to oxides and HF.
Otherwise, your sample should be fine, and I'd recommend not to do anything to it unless you need to use it.

Quote: Originally posted by itchyfruit

I was looking at a sealed container of SBF5 and it contained very light free flowing dark grey/black course powder(a bit like charcoal) thinking this was strange looking stuff,i looked it up and it should be a liquid.
The container's label read Antimony pentafluoride 25g
Toxic Corrosive
moisture sensitive
store under nitrogen
It also said something like 50w/t %graphite.

So my question is why does Wiki and others say it is a liquid when the container states 25g (i do realise some liquids are sold in grams) but why is it a solid or is it a gas on graphite or has it oxidised because it wasn't under nitrogen.
please help as i'm really confused