Sciencemadness Discussion Board - Semi metals or metalloids as anions: a preparation thread.

Semi metals or metalloids as anions: a preparation thread.

bismuthate - 20-10-2013 at 06:10

I have been interested in metals as anions for quite a while and I thought that we should have a thread that describes how to synthesise compounds with poor metals as anions. If anyone here has prepared one please describe the procedure.

I have changed the title to reflect what I think is a better expression of the original poster's intention in English.

Science Squirrel

[Edited on 24-10-2013 by ScienceSquirrel]

deltaH - 20-10-2013 at 06:40

Do you mean things like nickel antimonide?

bismuthate - 20-10-2013 at 06:42

Yes. Also things like aluminides, bismuthides, stannides, and more.

deltaH - 20-10-2013 at 07:27

By chance, I was looking at this wiki photo of nickel antimonide the other day... it's really stunning stuff, reminds me of red/pink gold.

Photo by Heinrich Pniok a.k.a Alchemist-hp from Wikimedia commons under these licensing conditions.

blogfast25 - 22-10-2013 at 05:15

Ammonium hexachlorostannate:

http://www.sciencemadness.org/talk/viewthread.php?tid=14593#...

Potassium hexachlorostannate, from pewter:

http://www.sciencemadness.org/talk/viewthread.php?tid=14668&...

[Edited on 22-10-2013 by blogfast25]

deltaH - 22-10-2013 at 08:18

If anybody is interested, the gentleman who made that photo of NiSb I posted in the beginning has just mailed me that he has a few grams left and is selling for $25/g, excl. postage... just thought I would pass that along. PM me for his contact details if interested. He says it's 'very nice and pure'

bismuthate - 4-11-2013 at 04:06

Hi. I just recived 20g of gallium

and I've decided to mak sodium thiogallate. Wiki (on it's page about gallium) says that it is synthesised by mixing sodium carbonate, gallium oxide and hydrogen sulfide. I couldn't find the syn thesis of sodium thiogallate elswhere, so I'd like to know if this route has been done by anyone. (I can find the synthesis for other thiogallates).

[Edited on 4-11-2013 by bismuthate]

deltaH - 4-11-2013 at 04:11

Quote: Originally posted by bismuthate

Hi. I just recived 20g of gallium

Wow... ambitious, best of luck, should prove to be really fun! Incidentally, was your gallium very costly?

bismuthate - 4-11-2013 at 04:24

It was $25.11 with shipping so it was pretty well priced. Oddly enough I had a gift card worth $25.11....

.
Maybe I shoul start out with calcium thiogallate... or barium I've found patents on those.

thebean - 6-11-2013 at 07:35

Bismuthate, please tell me how your thiogallate syntheses turn out. I'd be very interested to see samples and attempt them myself.

phlogiston - 6-11-2013 at 14:18

It is possible to make salts containing the Na- anion. They are called sodides or natrides. Some of these salts are stable at room temperature. The other alkali metals can similarly form alkides.

http://en.wikipedia.org/wiki/Alkalide

bismuthate - 6-11-2013 at 16:44

That's absolutely amazing, although I can't imagine what it would take to synthsise and store them. I am also unsure if NaK is a compound or merely an alloy.

I now have a crude set up for what I plan to do. It is a H2S generator that leads to a test tube with a stoichiemetric mix of BaCO3 and Ga2O3. After the gas is channeled through the test tube it will be lead through multiple copper sulfate solutions to absorbe the excess gas. Any flaws or improvements to be made?

Also I'd like to take a field trip to the land of magnificent tohubohu and madscience of the most theoretical and impractical type.

I was wondering if it would be possible to synthesise barium thiogallate from an excessive amount of H2S and anhydrous barium gallate at elevated temperatures.

DraconicAcid - 6-11-2013 at 16:47

Quote: Originally posted by bismuthate

That's absolutely amazing, although I can't imagine what it would take to synthsise and store them. I am also unsure if NaK is a compound or merely an alloy.

NaK is an alloy. To keep an alkanide stable, the cation has to be very stable towards reduction- ordinary alkali metal cations won't do (because Na⁺ + Na^- -> 2 Na is very favourable). You have to encase the sodium cation in a cryptand-type ligand to make sure it doesn't react with the sodide/natride anion.

bismuthate - 6-11-2013 at 17:28

Thanks for the quick response. On this subject I was reading about dilithium (an interesting Li-Li covalent bond containing compound) on wiki. I've got the dilithium prepare for warp speed.

[Edited on 7-11-2013 by bismuthate]

kristofvagyok - 7-11-2013 at 15:43

Quote: Originally posted by phlogiston

It is possible to make salts containing the Na- anion. They are called sodides or natrides. Some of these salts are stable at room temperature. The other alkali metals can similarly form alkides.

They are great!!!!!

I made K⁺K^-. It had a beautiful blue color and reacted readily with a lot things. I made an indole synthesis with this nice little thing(:

deltaH - 7-11-2013 at 16:23

Quote: Originally posted by kristofvagyok

Quote: Originally posted by phlogiston

They are great!!!!!

I made K⁺K^-. It had a beautiful blue color and reacted readily with a lot things. I made an indole synthesis with this nice little thing(:

Out of curiosity, which cryptand did you use (your formula doesn't suggest it)?

[Edited on 8-11-2013 by deltaH]

kristofvagyok - 7-11-2013 at 16:34

I used 18-crown-6 and a few other custom made crown ethers.

There is a few article where they describe blue coloration of solutions while boiling polyethers like diglyme with sodium-potassium alloy. It could be an inetesting experiment for anyone. I was totally amazed by the blue color what appeared on the surface of the metal.

The K⁺K^- is pretty reactive, if not freshly absolutized ether is used as a solvent the blue color will never really develop. Another good to know is, that it breaks up THF forming KOCH₂CH₂CH₂CH₂K if the solution is stored for a while or it heats up. This base is also a really strong base, sadly it is not so well soluble.

Also important to note that it will eat up the teflon coating of the stir bars in a few day

deltaH - 7-11-2013 at 16:36

Quote:

Also important to note that it will eat up the teflon coating of the stir bars in a few day

Good to know!

Mixell - 8-11-2013 at 05:10

I've made some germanium sulfate solution by displacing copper ions with solid germanium (in powder form). It is yellowish and highly acidic, probably due to an equilibrium with sulfuric acid and germanium dioxide (or may-be some intermediate between sulfate and oxide).

blogfast25 - 8-11-2013 at 05:55

Mixell:

Did you obtain this as a solid? Salts of highly charged, small cations (like Al3+

tend to be acidic:

[Al(H2O)n]3+(aq) + H2O(l) < === > [Al(H2O)(n-1)(OH)]2+(aq) + H3O+(aq)

And do you know the oxidation state of the Ge? II or IV?

[Edited on 8-11-2013 by blogfast25]

sbbspartan - 8-11-2013 at 07:16

Quote: Originally posted by bismuthate

I now have a crude set up for what I plan to do. It is a H2S generator that leads to a test tube with a stoichiemetric mix of BaCO3 and Ga2O3. After the gas is channeled through the test tube it will be lead through multiple copper sulfate solutions to absorbe the excess gas. Any flaws or improvements to be made?

Out of curiosity, how are you planning on making the Ga2O3 from the gallium?

[Edited on 8-11-2013 by sbbspartan]

Mixell - 8-11-2013 at 14:28

No, I've tried to desiccate it, but with no success.
The amount of copper I got points out to Ge⁴⁺.

The solution is very acidic (pH <1), probably due to the germanium cations scavenging O^-/OH^- from the water, leaving relatively free protons behind.

bismuthate - 8-11-2013 at 18:44

sbbspartan, I plan to heat the nitrate until decomposition. I will make the nitrate with gallium and nitric acid. However I think that I will postpone this and look further into the possibility of synthesising thiogallates from metal gallates.

blogfast25 - 9-11-2013 at 14:32

Bismuth:

Why not simply precipitate the Ga as Ga(OH)3? Assuming Ga metal is all you have right now, dissolve in dilute HCl (and make some video/photos! You don't see that everyday) and neutralise with ammonia to precipitate the hydroxide.

I'm not sure what route to thiogallate you're looking at but freshly precipitated and washed Ga(OH)3 is likely to be far more reactive than calcined Ga2O3.

bismuthate - 9-11-2013 at 16:15

Well blogfast, all of the procedures say that you should use gallium oxide and a metal carbonate. However as I said before I plan to make it from a gallate to increase purity. Hopefully it will work as I have not found this described anywhere. About the videos: I'm not sure I'll be able to make a video, although I'll try.
The basic idea of my newly devised (still not sure if it works) synthesis is to pass H2S over metal gallates.

[Edited on 10-11-2013 by bismuthate]

Tdep - 9-11-2013 at 17:27

Gallium trioxide? I did that by dissolving some gallium in hydrochloric acid (which took quite some time, only a bit faster than tin in my experience). This gallium trichloride was then neutralized with NaOH to precipitate gallium trioxide.

It was quite hard balancing the levels of acid to base, as any excess of either would cause the white precipitate to redissolve. But, I guess you want it to redissolve if you want to form sodium gallate (?)

And some pictures, as someone requested. Used the sort of black oxide layer that my gallium seemed to form that didn't look so good, so that's why it's black in the first photo. It eventually (after about a week of room temperature reacting) melted and formed quite beautiful silver balls that were great to watch slowly bubble away.

Also, sorry about the horrible dirty outside of the beaker haha. Quite ruins the photo

bismuthate - 9-11-2013 at 18:12

Thanks for the pics! On another note if I recall correctly the neutralization of GaCl3 yields Ga(OH)3.

Tdep - 9-11-2013 at 19:23

I mean, I did dry it using heat that would have decomposed the hydroxide so for me it's not a huge deal but reference:
Gallium oxide is precipitated in hydrated form upon neutralization of acidic or basic solution of gallium salt

Or is the 'hydrated form of the oxide' actually the hydroxide?

blogfast25 - 10-11-2013 at 06:08

Quote: Originally posted by Tdep

It was quite hard balancing the levels of acid to base, as any excess of either would cause the white precipitate to redissolve. But, I guess you want it to redissolve if you want to form sodium gallate (?)

If you don't want gallate to form, use ammonia to neutralise the GaCl3 with because NH3 is too weak a base to form Ga(OH)₄^- anions. With ammonia Ga(OH)₃.nH₂O will form only.

On the other hand, it may be advantageous to have the gallium as gallate to prepare the thiogallate. Gallate solutions are alkaline and alkaline solutions absorb H2S readily.

But will the substitution reaction (here schematic):

Ga(OH)₄^- === > Ga₂S₄^2- actually take place? Hmmm...

Quote: Originally posted by Tdep

Or is the 'hydrated form of the oxide' actually the hydroxide?

For all intents and purposes, yes. Varying degrees of hydration result from varying conditions of precipitation such as alkalinity, Ga concentration and temperature. But what precipitates is never stoichiometrically 'Ga₂O₃'.

Interesting how you found the reactivity towards HCl subjectively lower than that of Al. I kind of expected the opposite...

[Edited on 10-11-2013 by blogfast25]

bismuthate - 10-11-2013 at 06:17

My thoughts exactly. I believe that when Ga2O3 and metal carbonates are heated in the usual process they form gallates wich then proceed to react with H2S. However that way would cause impurities and require more heat, so I came up with this.
Another idea CaS+Ga2S3-->CaGa2S4?

blogfast25 - 10-11-2013 at 06:23

Quote: Originally posted by bismuthate

[...] are heated in the usual process they form gallates wich then proceed to react with H2S. However that way would cause impurities and require more heat, so I came up with this.
Another idea CaS+Ga2S3-->CaGa2S4?

What do you understand by 'the usual process'? Dry or wet?

CaS + Ga2S3 would have to be done by fusion. CaS hydrolyses like mad in water and is in any case hard to get.

Do you have any date/references on the solubility of some of these gallates? I've seen formulas like CdGa2S4 and SrGa2S4 for phosphors. No idea how they are prepared though.

bismuthate - 10-11-2013 at 06:39

Oh sorry well all ways are dry. The usual way is heating a metal carbonate with Ga2O3 and H2S gas. I can't find anything about the solubilities the only info I found was about phosphorescence and synthesis. The sulfide fusion idea is merely speculation.

blogfast25 - 10-11-2013 at 11:12

Quote: Originally posted by bismuthate

Oh sorry well all ways are dry. The usual way is heating a metal carbonate with Ga2O3 and H2S gas. I can't find anything about the solubilities the only info I found was about phosphorescence and synthesis. The sulfide fusion idea is merely speculation.

Ok. In that case you really need anhydrous Ga2O3. Easier to wash, dry and calcine Ga(OH)3 than pyrolyse Ga(NO3)3, IMO. The latter may be difficult to isolate and removing the last bits of nitrogen may also be hard to do. By contrast, any traces of NH4Cl in the precipitated and washed Ga(OH)3 will easily come off on heating.

[Edited on 10-11-2013 by blogfast25]

bismuthate - 10-11-2013 at 11:21

I only have an alcohol burner for heating. Heating the hydroxide would not decompose it with such a weak flame I fear.(Ga(NO3)3 decomposes a 250 celcitus) This is besides the point since I will use the gallate method.

blogfast25 - 10-11-2013 at 11:32

Quote: Originally posted by bismuthate

I only have an alcohol burner for heating. Heating the hydroxide would not decompose it with such a weak flame I fear.(Ga(NO3)3 decomposes a 250 celcitus) This is besides the point since I will use the gallate method.

Actually, the hydroxide would decompose well before the nitrate, in all likelihood.

bismuthate - 10-11-2013 at 11:38

Thats odd most sources I've seen say that it first decomposes into an oxide hydroxide first. Wiki says that it decomposes to Ga2O3 at 400 celcius.

bismuthate - 26-11-2013 at 08:29

Bad news I have failed to make sodium gallate repeatedly (my filter didn't work to filter Ga(OH)3 over and over and I lost it)

. Since I do not want to waste any more gallium I plan to try to synthesize sodium thioaluminate by the same process except replacing sodium gallate with sodium aluminate as a test run.

[Edited on 26-11-2013 by bismuthate]

Eddygp - 28-11-2013 at 11:10

Of course, if you have the necessary equipment, you can try to prepare a gallide, a telluride (love them) or a bismuthide.

bismuthate - 29-11-2013 at 14:28

Shame I don't.
Well, good news. Today I led H2S over less than a gram of sodium aluminate. At first the gas that pssed over it had no oder leading m to believe it was reacted. When I added HCl to the mystery product it bubbled and smelled like H2S, so it may be thioaluminate

bismuthate - 5-12-2013 at 18:14

Eddygp, you mentioned gallides. Do you have any info on their synthesis?