Sciencemadness Discussion Board - Pnictogen hydride acid-base chemistry

Pnictogen hydride acid-base chemistry

bismuthate - 10-12-2013 at 20:31

Phosphonium salts are very underresearched. Does anybody have experience with them? So anyway I was thinking of making PH4Cl. could this be done by the gas phase reaction of PH3 and HCl at rt? Also could PH4+ (or PH2-) salts react with Sb to yield elemental P?

[Edited on 11-12-2013 by bismuthate]

blogfast25 - 11-12-2013 at 06:05

Quote: Originally posted by bismuthate

Phosphonium salts are very underresearched.

No, they're not. But they're hard to produce at the home level because phosphine is so toxic and inflammable.

Sb? Huh?

bismuthate - 11-12-2013 at 12:41

Sb as in antimony. I was wondering if it could replace P in PH4+ or PH2- containing compounds.

DraconicAcid - 11-12-2013 at 12:49

Quote: Originally posted by bismuthate

Sb as in antimony. I was wondering if it could replace P in PH4+ or PH2- containing compounds.

Single replacement reactions occur in simple ions- you are not going to get a reaction of the form 4 PH₃ + 4 Sb -> 4 SbH₃ + P₄.

blogfast25 - 11-12-2013 at 12:51

Quote: Originally posted by bismuthate

Sb as in antimony. I was wondering if it could replace P in PH4+ or PH2- containing compounds.

Yeah, I know what Sb stands for

.

You mean 'replace' or 'displace'? Stibine does exist, as does AsH3 and BiH3. As one goes down the series these compounds are progressively harder to protonate. Hence AsH3 already requires superacids to get AsH4+ cations.

bismuthate - 11-12-2013 at 12:54

Ahh sorry.
Well has anyone dealt with phosphonium ions or PH2- (no idea what they're actually called)?
I know that quite a few people here do deal with strong toxins.
Yeah I meant displace. Funny you metioned SbH3 since that is actually the thing that made me make this thread. (I was going to be using SbH3 to make NaSbH2 and I saw the other XH4 ions (x standing for a pnictogen (hey I used a parenthese in a parenthese)) and they where realy interesting (I wonder what it would take to protonate BiH3(I would love to have a bismuthonium salt))) (Oh! Well that was a hopelessly jumbled pile of parentheses

)

[Edited on 11-12-2013 by bismuthate]

[Edited on 11-12-2013 by bismuthate]

[Edited on 11-12-2013 by bismuthate]

DraconicAcid - 11-12-2013 at 13:09

I've never worked with either, but I used to work with a guy who made KPPh₂ as an intermediate in an organic synthesis (he got it by reacting thriphenylphosphine with potassium in some ether; he was making a fancy ligand).

Cotton & Wilkinson (4th ed) state that phosphonium chloride and bromide will dissociate into phosphine and hydrogen halide below 0oC; the iodide is more stable. Water will completely hydrolyze phosphonium salts. It does not mention analogues of the amide anion. Greenwood & Earnshaw mention it, but do not name it.

bismuthate - 11-12-2013 at 13:16

Well I know that
NaNH2+AsH3==>NaAsH2+NH3 so I can predict that phosphine will behave the same way.

DraconicAcid - 11-12-2013 at 13:23

G&E point out that phosphine will dissolve in liquid ammonia to give ammonium whatever-you-call-that-anion. (That's G&E's Chemistry of the Elements, 2nd Ed) So you don't need to use the amide, just the anhydrous liquid.

Probably "ammonium dihydrogen phosphide".

bismuthate - 11-12-2013 at 13:33

i wonder if bubbling PH3 through liquid SbH3 would yield PH4SbH2. I would try that if it weren't so bloody dangerous.
By the way I believe that the title should be changed to pnictogen hydride chemistry.

[Edited on 11-12-2013 by bismuthate]

DraconicAcid - 11-12-2013 at 13:46

Quote: Originally posted by bismuthate

i wonder if bubbling PH3 through liquid SbH3 would yield PH4SbH2. I would try that if it weren't so bloody dangerous.
By the way I believe that the title should be changed to pnictogen hydride chemistry.

[Edited on 11-12-2013 by bismuthate]

I doubt it- phosphine's a lousy base. But bubbling ammonia through liquid stibnine should work.

bismuthate - 11-12-2013 at 14:11

Good point however I bet H2SO4 could protonate it.
I may decide to make NH4SbH2 like that (I planned to react it wit Li).
I also wonder if SbH4 salts are possible with weak anions (carbicde, azide, ect) through metaphisis reations.

DraconicAcid - 11-12-2013 at 14:20

Quote: Originally posted by bismuthate

Good point however I bet H2SO4 could protonate it.
I may decide to make NH4SbH2 like that (I planned to react it wit Li).
I also wonder if SbH4 salts are possible with weak anions (carbicde, azide, ect) through metaphisis reations.

G&E say "there is little tendency to form the onium ions MH₄⁺ analogous to MH₄⁺. Hoever, very recently the thermally unstable salts [AsH₄][SbF₆] (decomp. -40 oC), [AsH₄][AsF₆] (d. -75 oC) and [SbH₄][SbF₆] (d. -70 oC) have been isolated as colourless air- and moisture-sensitive crystals."

bismuthate - 11-12-2013 at 14:41

Thats odd that it's so unstable as SbF6 is a rather strong anion.
I bet that an attempted metathesis reation with carbides or azides would just end in an explosion though

blogfast25 - 11-12-2013 at 14:43

Quote: Originally posted by bismuthate

(I wonder what it would take to protonate BiH3(I would love to have a bismuthonium salt)))

Well, you can't have one, so there

But preparing small amounts of BiH3 isn't too hard, it's similar to Marsh for arsine. But it's very unstable... It's discovery is famously linked to the discovery of a particular radio isotope (can't remember which one right now) at the dawn of age of nuclear physics.

bismuthate - 11-12-2013 at 14:48

biH3 could by prepare by the hydrolysis of bismuthides I believe.
Also I would hypothesize reacting ammonia with bismuthane gas would yield NH4BiH2. that would be a very interesting salt.

bismuthate - 11-12-2013 at 18:17

Would NH4PH2 further react with NH3 to yield (NH4)3P?
Also I would think that I would be able to react NH4SbH2 with PH4Cl to obtain PH4SbH2 I wonder how stable that is.

DraconicAcid - 11-12-2013 at 20:11

Quote: Originally posted by bismuthate

Also I would think that I would be able to react NH4SbH2 with PH4Cl to obtain PH4SbH2 I wonder how stable that is.

That would probably give you PH₃ and SbH₃.

Brain&Force - 11-12-2013 at 21:33

Did my thread for uncharacterized compounds inspire this?
My internal etymology-man suggests phosphanide, arsanide, stibanide, and bismuthanide for the ions. I know the first two are correct; Google gives relevant results fo the first two. (Perhaps it is phosphinide, arsinide and stibinide, derived from the gas names.)
This is my guess from the IUPAC name for SH^-, sulfanide.

bismuthate - 12-12-2013 at 04:31

It is indeed phosphinide, Although if it were up to me I like the name phosphomide.
DraconicAcid, yes but at <0 temps would I would suspect that PH4SbH2 would form as an almost instantly decomposing intermediate.